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  • Characterization Study of Temper Embrittlement of Chromium-Molybdenum Steels API PUBLICATION 959 MAY 1982 American Petroleum Institute 1 11 2101 L Street, Northwest Washington, D.C. 20037COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLa959 8 2 M 0 7 3 2 2 9 0 0087Ll94 7 m Characterization Study of Temper Embrittlement of Chromium-Molybdenum Steels Refining Department API PUBLICATION 959 MAY 1982 American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • __" A P I PUBL*757 8 2 H 0 7 3 2 2 7 0 0 0 8 7 4 7 5 7 i Nothing contained any API publication is be construed as granting any in to right, by implication or otherwise, for the manufacture, sale, or use in connection with any method, apparatus, or product covered by letters patent. This publication maybe used by anyone desiring to do so. The Institute hereby expressly disclaims any liability responsibility for loss or damage resulting from or its use;for theviolation of any federal, state, municipal regulation with which or an API publication many conflict; for the infringement of any patent resulting from or the use of an API publication, Every effort has been by the Institute to made assure the accuracy and reliability of the data presented. Copyright O 1982 American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API P U B L * 7 5 7 8 2 W 0732270 0087496 O W PmFACE At the October 1973 P Refining meeting, it was brought to the AI attention of the Committee on Refinery Equipment that 2-1/4Cr-1 Mo steel, an alloy frequently used to build hydrotreater reactors, was susceptible of to temper embrittlement. Reactors constructed this alloy could poten- loss of toughness. The embrittlement tially experience a considerable occurs partly during shop fabrication heat treatments, but more signifi- cantly, as a result operating in the embrittling temperature range. of Responding to this problem, CRE established a Task Group on Temper Embrittlement with members from the Subcommittees on Corrosion and on Pressure Vessels and Tanks.The task group was given two objectives: 1. To review the existing metallurgical data and research programs, and to recommend what approach should be taken to avoid embrittlement prob- lems with existing vessels. for 2. To recommend what further work was required to develop steels future pressure vessels which would be immune or less susceptible to temper embrittlement. On July 30, 1974, the API issued a cautionary letter prepared by the task groupto managers of all refineries in the United States and Canada. It alerted plant operators to the concern for in-service embrittlement of low alloy chrome-moly steels, and especially of 2-1/4Cr-1 Mo in thick sections. It also suggested precautions that should be taken to minimize the probability of brittle fracture inembrittled material. Earlier, at the May1974 Refining meeting, CRE accepted a task group proposal that P support a multiyear program to characterize the temper AI embrittlement susceptibility commercial plate, forging, and welds used of in reactors. The program would investigate the extent of embrittlement that might exist in operating vessels and how predict the embrit- to best tlement that could occur. In the spring of 1975, Westinghouse Research Corporation was selected as contractor for a 5-year characterization research program as outlined by the task group, with Dr. Shaw J. Bevil as principal investigator. A total of 64 samples, mostly 2-1/4Cr-1 Mo, but a few 1-1/4Cr-1 Mo and 3Cr-1 compositions, were provided by of Mo member companies, by steel suppliers, and by vessel fabricators. The 64 samples represented a large range of commercially produced steels, and included qualification welds, croppings from forgings, and nozzle and manway cutouts from plate ranging in thickness up to 6 inches. The characterization program was divided into Phases II. I and Phase I included a 64-sample study of the microstructure, grain size tensile properties, hardness, chemistry, including tramp elements, heat treatments, and toughness. Toughness data included determination of tran- sition temperatures before and after short time step-cool embrittlement heat treatment and of the shift in transition temperature resulting from the induced embrittlement.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • For PhaseII, 25 heats were selected for additional embrittlement study. These heats were chosen to represent both the typical and the extremes in chemistry and in susceptibility to temper embrittlement as II was the measured by the step-cool test. The main thrust of Phase characterization of these alloys for embrittlement during isothermal exposure at five temperatures from F 950 F for times up 20,000 650 to to hours. These temperatures were chosen to span the range typical of service condit ions. The report which follows is a summary covering the Westinghouse characterization work and several ancillary studies, which developed during the nearly 6 years of work by the task group and Dr. Shaw. At the outset, the P program recognized that the characterization AI study could provide much needed. information about the temper embrittle- low ment- behavior of commercial alloy Cr-Mo steels used in reactors. It was not designed, however, probe the temper embrittlement mechanism. to Coincidentally, in late 1974, the Metals Properties Council Task Group on Tramp Elements in Pressure Vessel Steels was considering a proposal by Dr. C. J. McMahon, Jr., Department of Materials Science and Engineer- ing, University of Pennsylvania, to study the mechanism of temper em- brittlement, particularly with respect to the effect of tramp elements. The A I task group also reviewed the proposed program and conciuded that P it was a highly desirable supplement to the characterization study. As a result, P entered into an agreement with the Metals Properties AI Council for joint API/MPC support of McMahons three-phase, 5-year mechanism study. The primary objective was study, using laboratory to heats of controlled chemistry, the individual and synergistic embrittl- ing poeency of the elements manganese, phosphorus, silicon, antimony, and tin. A number of significant conclusions on the effects of these elements were derived from this study. Some of these data have been published in an article appearing in Vol. 102, of the Transactions 1980, ASME, Journal of Engineering Materials and Technology. Other supplement- ary papers are in process of publication, and a final report is now being prepared by Dr. McMahon. The AI Temper Embrittlement Characterization Study benefited P strongly from the support steel manufacturers and vessel fabricators. of Their representatives were active ex-officio members of the task group; their industrial backgrounds made their input to the program especially valuable. This is an outstanding example of the benefits derived to be from close cooperation between supplier and user. As a result of AI characterization study and the jointly supported P the API/MPC mechanism study, along with large individual research programs by some steel suppliers and vessel fabricators, which were at least partly stimulated by the API program, there is now a much better under- standing of the causes and implications of temper embrittlement for reactors built up about 1975. As a result the cooperative effort, to of it is now possible obtain hydrotreator reactors, both in the United toCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 0087478 4 m Statesandabroad,withfargreaterinitialtoughnessandwithrelatively l i t t l e s u s c e p t i b i l i t yt ot e m p e re m b r i t t l e m e n t . It is w i t h a s t r o n gs e n s e of a c h i e v e m e n tt h a tt h et a s kg r o u ps u b m i t st h i s summary r e p o r t .R e a d e r s - are c a u t i o n e d t h a t t h e c o n c l u s i o n s i t draws are a p p l i c a b l e t o materials i nr e a c t o r sp r o d u c e d up t o a b o u t 1975. They are n o t a p p l i c a b l e t o t h e plate,forgings,andweld metal a v a i l a b l e t o d a y f r o m t h o s e m a n u f a c t u r e r s utilizing the necessary controls to produce material havinglowtemper e m b r i t t l e m e n ts u s c e p t i b i l i t y .F i n a l l y , i t s h o u l db er e c o g n i z e dt h a tt h e user has the responsibility to specify that material w i t h low e m b r i t t l e - ment s u s c e p t i b i l i t y i s r e q u i r e d , a n d t h a t i t cannotbeassumedthat all low a l l o y Cr-Mo material a v a i l a b l e t o d a y meets t h i s c r i t e r i o n . AI TASK GROUP ON TEMPER EMBRITTLEMENT F APRIL 1982COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • CONTENTS Section Page III PHASE I: STEP-COOLED EMBRITTLEMENT EXPERIMENTS AND MATERIAL CHARACTERIZATION ...... o................. 7 IV PHASE II: ISOTHERMAL EMBRITTLEMENT EXPERIMENTS....o*o.. .**o14 VI1 PREDICTION OF LONG^ TERM ISOTHERMAL EMBRITTLEMENT. 19 X THE SEGREGATION OF ELEMENTS TO GRAIN BOUNDARIES I N Cr-Mo STEELS AFTER 20,000 EIR ISOTHERMAL EMBRITTLEMENT ASSESSED BY AUGER ~ALYSISo....oo.o............o..oo.oo.ooooooose.ooo25 XII A STUDY OF THE EFFECT OF HIGH PRESSURE HYDROGEN ON THE TEMPER EMBRITTLEMENT CHARACTERISTICS O &-MO F STEELS.ea.ooe.31COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • " . A P I PUBL*757-82 W 0 7 3 2 2 3 0 0087500 9 W APPENDIX: DISCUSSION OF THE CHARPY TEST. ........................... A - l ........A-2 (a) Sources of Error in Charpy Impact Test Data (b) The Charpy Specimen Fracture Appearance ............A-1 Temperature Figures A l to A4 ......................................... A-6 (c) Experimental Scatter in the 40 ft-lb Transition ........................................... A-3 viii " " . ."COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*759 8 2 m 0732270 0087501 O m CHARACTERIZATION STUDY OF TEMPER EMBRITTLEMENT OF CHROMIUM-MOLYRDENUM STEELS R . J. Shaw Westinghouse R&D Center P i t t s b u r g h ,P e n n s y l v a n i a1 5 2 3 5 AB S TRACT A c o m p r e h e n s i v ee v a l u a t i o no ft h es t e p - c o o l e da n di s o t h e r m a l embrittlementof Cr-Mo p r e s s u r e vessel steels (A387) h a sb e e nc a r r i e d o u t . The p r i m ep u r p o s eo ft h i sp r o j e c t was t oc h a r a c t e r i z et y p i c a l c o m m e r c i a lr e a c t o r s steels and weldments i n terms oftoughness and o t h e r p h y s i c a lp r o p e r t i e sp r i o rt ob e i n gp l a c e di n service and thechanges a n t i c - i p a t e di nt o u g h n e s sd u et ol o n g term service a t elevatedtempera- t u r e s .I nP h a s e I oftheprogram, 64 s u p p l i e d s t e e l s were c h a r a c t e r i z e d i n terms of t e n s i l e p r o p e r t i e s , m e t a l l o g r a p h i c f e a t u r e s and a n a l y t i c a l c h e m i s t r y .I nt h i sp h a s et h ec h a n g ei nt h et r a n s i t i o nt e m p e r a t u r ed u e t os t e p - c o o l e de m b r i t t l e m e n t was e v a l u a t e d from Charpy impact curves. I n Phase II, 25 s e l e c t e ds a m p l e s were i s o t h e r m a l l ye m b r i t t l e df o r 1,000, 10,000 and 20,000 hours a t 650, 725, 800, 875 and 9500F. S p e c i f i c r e l a t i o n s h i p sb e t w e e ns a m p l ec h e m i s t r y ,s t r e n g t hl e v e lo rs t r u c t u r e s were s t u d i e d . Based upon comparison Phase of I and II d a t a ,a na p p r o x i - mate r e l a t i o n s h i pb e t w e e nt h es t e p - c o o l e de m b r i t t l e m e n ta n dt h e i s o t h e r m a l m b r i t t l e m e n t i s derived. e This paper includes study the of repeatedde-embrittlement on two i s o t h e r m a l l ye m b r i t t l e d steels and t h e e f f e c t o fs t r e n g t h level and s t r u c t u r e on t h ei s o t h e r m a le m b r i t t l e m e n t of sample one of s t e e l . Subsidiary experiments performed Phase in I L of t h e program i n c l u d e t h e e f f e c t of highpressurehydrogen(3500psig) on temperembrittlement,fracturetoughnessmeasurements (JIc) on one samplefractographic valuation , e of i s o t h e r m a l l y m h r i t t l e d steels and e - a n Auger E l e c t r o n S p e c t r o s c o p i c e v a l u a t i o n o f g r a i n b o u n d a r y s e g r e g a t i o n of i s o t h e r m a l l ye m b r i t t l e ds a m p l e s . A s a r e s u l t of the API Temper EmbrittlementCommitteeefforts,theNationalBureauofStandardshas produced a s o l i ds t a n d a r d of 2-1/4Cr - 1Mo s t e e l (StandardReference Material 1 2 7 0 ) .S i n c et h ei n t e r p r e t a t i o no ft h ed a t ad e p e n d s upon t h e experimental s c a t t e r a na p p e n d i xh a sb e e nd e v o t e dt ot h ec h a r a c t e r i z a - t i o n oftheCharpyimpact t e s t procedure.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API P U B L * 7 5 7 8 2 W 0 7 3 2 2 9 0 0 0 8 7 5 0 2 2 KEY FOR ARBREVIATIONS AND SYMBOLS 40 f t - l b TT 40 f t - l b r a n s i t i o n e m p e r a t u r e l s o ( 4 0 ) T T a T FATT F r a c tA pe e a r aT r a n s i tT o m p e r a t u r e ur p nce i en (50% Shear) AT ( 4 0 ) h i f t S in 40 f t - l b TT Due t o Temper F m b r i t t l e m e n t AFATT S h iifnt FATT Due t o Temper F m b r i t t l e m e n t ATT T r a n S ieii f tp e r a t u r e i n ht m n s o T Subscriptsto FATT and 40 f t - l b TT U U n e m b r i t to e d lr as r e c e i v e d d i t i o n con ( i . e . d h go f e t ee re e m h r i t t l e m e n td e r i v e d from c o o l i n gt h r o u g ht h et e m p e r e m b r i t t l e m e n tr a n g eo ft e m p e r a t u r e sa f t e rt h ef i n a lh e a t treatment) D D e - e m h r i t tc e d d i t i o n lon - (1100oF, 2 h r s , water quench t o . remove a l l temper embrittlement) E S t e p - c o o l e d ic t ln d i t i o n embr t o e (see page 11) 1,000, 1 0 , 0 0 0 , s t a n df o rt h e number ofhoursofisothermalembrittlement 20,000 SM E Scanning Electron Microscope AES Auger E l e c t r o n S p e c t r o g r a p h IG Intergranular CL Cleavage DM Dimpled Rupture CB I Chicago Bridge Iron and JSW S tJ a p a n eel Works - WRDC Westinghouse R&D Center F OR Forging. PLA Plate SW A Submerged Arc Weld ESW Elec t r o s l a g Weld Material Key S A M S h i e l d e d Metal Arc Weld 1 1-1/4Cr - 1/2Mo 2 2-1/4Cr .- 1Mo 3 3Cr - 1Mo M S tM a rttu rn s i t i c ruc e e QBM Quenched M a r t e n s i t e -S t aun i t er e Rr i ctu B S t r u c t Br e n i t e u ai F -P F e r r i t e - PS t rru i tte r e ea l c u A FractureToughnessParameter Used i n A s s e s s i n g Low S t r e n g t h High D u c t i l i t y Metals J An E m b r i t t l e m e n tF a c t o r , (Mn + S i ) ( P + Sn) x l o 4 (WtX) - x A F m b r i t t l e m e n tF a c t o r , n (P + 4Sn f 5 A s + Sb) x lo-* (PP) X -? " -COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLr959 82 m 0732270 0087503 Characterization Study of Temper Embrittlement of Chromium-Molybdenum Steels I INTRODUCTION In 1975 t h e API awarded a c o n t r a c tt oW e s t i n g h o u s e R&D Center (WRDC) t oe v a l u a t et h et e m p e ra n b r i t t l e m e n tc h a r a c t e r i s t i c so f Cr-Mo p r e s s u r e vessel steels. The steels are d e s i g n a t e d A387 i nP a r t 4 of t h e A T Book ofStandards. SM Most of thesamplessupplied were of Grade .22(2-1/4Cr - 1Mo) and a fewsamplesofGrades 1 and 1 21 were a l s o included (1-1/4Cr - - 1/2Mo, 3Cr 1Mo). The 64 samples received r e p r e s e n t e d . a largerangeofcommerciallyprodpced steel i n c l u d i n g q u a l i f i c a t i o nw e l d si n1 - i n .a n d6 - i n .p l a t e ,l a r g en o z z l ec u t - o u t sa n d randomly shaped pieces of f o r g i n g and p l a t e material. These materials h a dr e c e i v e dh e a tt r e a t m e n tt y p i c a l of h y d r o - t r e a t e rr e a c t o rf a b r i c a - . t i o n . The samples were t y p i f i e d by a simplecode as f o l l o w s : FOR Forging PU Plate SW A Submerged Arc Weld EST4 E l e c t r o s l a g Weld S A M S h i e l d e d ?.letal Arc Meld 1 1-1/4Cr - 1/2Mo 2 2-1/4Cr - 1Mo 3 3Cr - 1Mo T h u s ,t h r o u g h o u tt h et e x t , 1 PLA means1-1/4Cr - 1/2Mo P l a t e material, 2 S W means A 2-1/4Cr - 1Mo Submerged Arc Weld material and so on. The o b j e c t i v e o f t h i s program was t o c h a r a c t e r i z e t y p i c a l com- mercial r e a c t o r s steels and weldments in terms oftoughness and o t h e r p h y s i c a lp r o p e r t i e sp r i o rt ob e i n gp l a c e di n service and thechanges a n t i c i p a t e di nt o u g h n e s s due t o long time s e r v i c e a t elevatedtempera- t u r e . It i s i m p o r t a n tt on o t et h a tt h e s e materials were t y p i c a lo f commercialproductionandfabrication up toabout1975, and are - not r e p r e s e n t a t i v eo ft h ep l a t e ,f o r g i n g s andweld metal, havinglowtemper e m b r i t t l e m e n ts u s c e p t i b i l i t ya v a i l a b l et o d a y [ I l . Phase I of t h e p r o j e c ti n c l u d e dt h em e t a l l o g r a p h ya n dg r a i ns i z e ,t h et e n s i l e p r o p e r t i e s and t h eR o c k w e l lH a r d n e s s e s ,t h ea n a l y t i c a lc h e m i s t r i e s includingthetrampelements,theheattreatmentsandCharpyimpact test d a t a . The latter y i e l d e dt h eF r a c t u r eA p p e a r a n c eT r a n s i t i o n Tempera- t u r e s (FATT) and t h e 40 f t - l bT r a n s i t i o nT e m p e r a t u r e s( 4 0f t - l b TT) f o r t h e steels i nt h eu n e m b r i t t l e da n ds t e p - c o o l e de m b r i t t l e dc o n d i t i o n . The terms AFATT and AT(40) r e f e r t o t h e c h a n g e i n FATT and t h e 40 f t - l b TT due t o temper e m b r i t t l e m e n t . 1 f .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 008750Ll b m The main p a r tPhase of i s o t h e r m a l m b r i t t l e m e n t of e 25 II was t h e r a c t e r i z a t io en cha steels a s s e s s e d n h a s e i P hof I. F i v e a i s o t h e r m a la n b r i t t l e m e n tt e m p e r a t u r e s were chosen a t 750F i n t e r v a l s from 6500 t o 9500F. Tests t om e a s u r et h e amount temper of embrittlement were c a r r i e do u ta f t e r1 , 0 0 0 ,1 0 , 0 0 0 and 20,000hours. A number of studies were also performed i n t h i s time.. These were: o The e f f e c to fr e p e a t e dd e - e m b r i t t l e m e n to ft h e steel. o The e f f e c t o fs t r e n g t h level and s t r u c t u r e . o Auger a n a l y s i so fg r a i nb o u n d a r i e so fe m b r i t t l e d steels. measurements. O JIC o E f f e c t ofhighpressurehydrogen on temperembrittlement. o I s o t h e r m a le m b r i t t l e m e n t of 1-1/4Cr. and 3Cr steels. By t h e endof1976 thefirstphase oftheprogramhadbeen completed. A t t h i sj u n c t u r ei nt h e program a number of discrepancies, b e t w e e nt h ed a t ag e n e r a t e d a t WRDC a n d o t h e r l a b o r a t o r i e s , were brought t ol i g h t . T h e s ei n c l u d e dt h ev i s u a lr e a d i n g so ft h ep e r c e n t a g eo f b r i t t l e f r a c t u r e on t h eC h a r p ys p e c i m e n s ,t h ec o n c l u s i o nt h a t AFATT was n o ta l w a y se q u a lt o AT(40), a b s o l u t e d i f f e r e n c e s i n t h e Charpyimpact e n e r g yc u r v e sa n dt h er e s u l t so ft h ea n a l y t i c a lc h e m i s t r i e s .I na d d i - t i o n , i t was found t h a ti nP h a s e I oftheprogram WRDC had used a Charpy specimenorientationwhich was d i f f e r e n t t h a n t h e Ö n e c o n v e n t i o n a l l y used by API. As a consequence, a number o fs u b s i d i a r ye x p e r i m e n t s were i n i t i a t e dt oc l a r i f yt h ev a r i o u si s s u e s .T h e s ei n c l u d e d a comparative Charpyimpact test s t u d yb e t w e e nJ a p a nS t e e l Works (JSW) and WRDC and a c o m p a r a t i v ef r a c t u r es u r f a c ee v a l u a t i o ns t u d yb e t w e e n Chicago-Bridge and I r o n ( C R & I ) and WRDC (see Appendix). A t t h e same time, s i n c et h e specimensforPhase II oftheprogram were machined i nt h ec o n v e n t i o n a l API o r i e n t a t i o n ,e x p e r i m e n t sd e s i g n e dt oe s t a b l i s ht h er e l a t i o n s h i p betweenthePhase I and Phase II o r i e n t a t i o n s were c a r r i e d o u t . Inaddition,the AI Task Group i n i t i a t e d a roundrobin P com- p a r a t i v ea n a l y s i so fs a m p l e s and a l s or e q u e s t e dt h eN a t i o n a lB u r e a uo f S t a n d a r d st oe s t a b l i s h a s o l i d 2-1/4Cr - 1Mo S t a n d a r df o rs p e c t r o g r a p h i c a n a l y s i s . A s a d i r e c t r e s u l t of the API Task Group e f f o r t s ,t h i ss t a n - d a r dd e s i g n a t e d S M 1270, i s now a v a i l a b l e f o r p u b l i c p u r c h a s e R from NBS. The s u b s i d i a r ye x p e r i m e n t s were c a r r i e do u td u r i n gP h a s e 1 of t h e 1 p r o j e c t which was concluded i n 1980. This paper reviews primary the r e s u l t s of t h e program.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 W 0 7 3 2 2 7 0 0087505- 8 W II. GENERAL CONCLUSIONS Thispaperhasbeenorganized s o t h a tt h ev a l u e of t h ee x p e r i - mental r e s u l t s c a n b e a s s e s s e d a n d t h e n t h e i n f o r m a t i o n g e n e r a t e d h a s beenreviewed i n terms o ft h e s ec o n s i d e r a t i o n s . It c a nb eo b s e r v e dt h a t a small p o r t i o n of t h e s a m p l e s i n t h e u n e m b r i t t l e d (as r e c e i v e d )c o n d i t i o ne x h i b i t e dt r a n s i t i o nt e m p e r a t u r e s above normal ambient temperature (+50°F). Similarly, the number of s a m p l e se x h i b i t i n g TT a b o v en o r m a la m b i e n tt e m p e r a t u r es i g n i f i c a n t l y i n c r e a s e da f t e rs t e pc o o l i n go rl o n g - t i m ei s o t h e r m a le x p o s u r e .S i n c e thesamples were s e l e c t e dt ob et y p i c a lo fc o m m e r c i a lr e a c t o r materials, t h e s e r e s u l t s can be compared toreactorspriorto service ( u n e m b r i t t l e d s a m p l ec o n d i t i o n ) and a f t e rp r o l o n g e ds e r v i c e( s t e pc o o l e do r isothermally xposed ample ondition). ee igure e s c S F 44. I n t h e Appendix,"DiscussionoftheCharpy Test," i t was c o n c l u d e dt h a tt h eF r a c t u r eA p p e a r a n c eT r a n s i t i o nT e m p e r a t u r e (FATT) was a subjective measurement and was o p e nt oc o n s i d e r a b l ee r r o r .F o rt h i s r e a s o nm o s to ft h ed i s c u s s i o nh a sb e e nb a s e du p o nt h e 40 f t - l b T r a n s i - t i o nT e m p e r a t u r e ( 4 0 f t - l b TT) which i s r e l a t i v e l y n o n s u b j e c t i v e m e a s u r e m e n to ft h ee f f e c to ft e m p e r a t u r e . Even so, i t was f o u n dt h a t c o n s i d e r a b l e scatter c o u l d e x i s t i n t h e 40 f t - l b TT. A u n i v e r s a l i n d u s t r i a l problem i s t h e p r e d i c t i o n o f l o n g - t e r m ( u s u a l l yy e a r s ) service d e g r a d a t i o no f a material component. The u s u a l approach i s t o make p r e d i c t i o n s b a s e d upon c a r e f u l l y c o n s t r u c t e d s h o r t - term s c r e e n i n g tests. The c o n s t a n ti n e v i t a b l eq u e s t i o n i s "how w e l l do t h es c r e e n i n gm e t h o d o l o g i e sr e p r e s e n t - t h el o n g - t e r mc h a r a c t e r i s t i c s ? " The API program a d d r e s s e st h i sp r o b l e mf o rt e m p e re m b r i t t l e m e n tv e r y d i r e c t l y . In Phase I t h es h o r t - t e r ms c r e e n i n g t e s t f o rt e m p e re m b r i t t l e - ment ( t h es t e p - c o o l e de m b r i t t l e m e n tt e s t ) i s e v a l u a t e d and t h e n compared w i t hi s o t h e r m a le m b r i t t l e m e n td a t au pt o2 0 , 0 0 0h r .i nP h a s e II. Even though s i g n i f i c a n te x p e r i m e n t a l scatter e x i s t e d i n t h e d a t a , enoughexperiments were c a r r i e do u tt of o r m u l a t ea p p r o x i m a t e e x p r e s s i o n sr e l a t i n gt h ei s o t h e r m a le m b r i t t l e m e n tt ot h es t e p - c o o l e d e m b r i t t l e m e n t . The r e s u l t sg e n e r a t e d from t h ed a t ab a s eo ft h i s program a p p e a rt o show t h a tt h es t e p - c o o l e de m b r i t t l e m e n tc a nb er e l a t e dt ot h e I s o t h e r m a le m b r i t t l e m e n tb u t i s n o te q u a lt ot h ev e r yl o n g - t e r m embrittlement of a s t e e l . In f a c tt h es t e p - c o o l e de m b r i t t l e m e n ta p p e a r s t oc o r r e l a t ew i t h 250-hr. isothermal embrittlement a t 875F. However t h es t e p - c o o l e de m b r i t t l e m e n ts c r e e n i n g t e s t shouldnotbereplacedwith 250-hr. i s o t h e r m a le m b r i t t l e m e n tw i t h o u tf u r t h e re x p e r i m e n t st oc o n f i r m 3COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • the prediction from Equation4 ) , page 21. This equation is primarily ( for 2 1/4 Cr 1 Mo steels. The equation, developed from the complete AT 0 ) data set, suggests that the 30-year in-service embrittlement, ( 4or 3 40 ft-lb TT is equal to times the step-cooled ft-lb Transition Temperature shift. Attempts to correlate the composition of a steel to the observed embrittlement indicated too many variables were present to formulate a reasonable regression analysis with the (statistically) disorganized i21 data available. The correlation with the often employed “J-factor” viz. (Mn + Si) (P + Sn) x 104 was relatively poor for data from weld metal, plate and forgings- Figures 4 (a) and (b). However, this cor- relation is not intended for weld metal and the correlation for plate and forging (black points) is comparable with that of similar studiesi31 Some of the scatter in the data for the plate and forging may indicate that the steel processing procedure is an important variable in the A387 Class 22 steel. The resultsof the PhaseII isothermal embrittlement tests may be summarized as follows: (1) 800- The maximum isothermal embrittlement occurred in the 9 50°F range. (2) Embrittling susceptibility varied widely in the 25 samples. Some reached peak embrittlement at 800°F or 875OF after 20,000 hr. exposure, while some had apparently not reached maximum embrittlement after 20,000 hr. at 950OF. (3) A possibility of embrittlement was found half of the in 65O0F. samples isothermally embrittled at (4) After 20,000 hr. exposure, the extremes and average values of the 40 ft-lb Transition Temperature for the 1 /2 Cr - 1 4 Mo samples were as follows: Exposure Average 40 foot-pound Range of40 foot-pound Transition Temperature Transition Temperature (OF) Temperature (OF) ( O F ) -___. - Min’ .~ MaxJ’ 650 - 11 - 115 + 55 725 - 8 - 100 + 60 8170 + 22 - 75 + 100 875 + 34 - 75 + 140 950 + 24 - 55 + 100 J. n Minimum and Maximum values are not for the same sample but of illustrate the range transition temperatures observed.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 0087507 (5) Of t h et w e n t yt h r e e 2 1 / 4 C r , one 1 C r and one 3Cr samples i s o t h e r m a l l ya g e d , a t o t a l of twelve s a m p l e se x h i b i t e d a 40 ft-lbtransitiontemperaturehigherthan 500F - which i s f r e q u e n t l yu s e dt ot y p i f yt h ea m b i e n tt e m p e r a t u r e - a t one o r moreof t h e 5 agingtemperatures,andforoneormoreof t h e 3 aging times. The breakdown by materials type and alloytype is giveninTable 29(a) and ( b ) . (6) Even t h o u g h h e a t a a s e t d b i s small, i t s u g g e s t ss t r o n g l y t h a t 2 1 / 4 C r weld metal h a s a - h i g h e r s u s c e p t i b i l i t y t o t e m p e re m b r i t t l e m e n tt h a np l a t eo rf o r g i n g s - Table29(b). (7)Because of t h e small d a t ab a s e , no f i r mc o n c l u s i o nc a nb e drawn a b o u tt h ei s o t h e r m a le m b r i t t l e m e n t of 1 C r and 3Cr a l l o y s , b u t i t would appearweld metal o fb o t ha l l o y sh a v e some s u s c e p t i b i l i t yt oe m b r i t t l e m e n t . In g e n e r a l ,t h eu p p e rs h e l fi m p a c te n e r g y ,w h i c hr e f l e c t st h e toughnessofthe s t e e l , was not s i g n i f i c a n t l y changed from the u n e m b r i t t l e dc o n d i t i o nt oe i t h e rt h es t e pc o o l e de m b r i t t l e m e n to rt h e i s o t h e r m a l l ye m b r i t t l e dc o n d i t i o n . The e f f e c t ofrepeatedde-embrittlement a t llOOOF f o r 2 h r s . on 8750F i s o t h e r m a le m b r i t t l e m e n t( i nf u l l yp o s t weld h e a tt r e a t e ds p e c i - mens) showed t h a t t h e d e - e m b r i t t l e d c o n d i t i o n was approximately a con- s t a n t . It was concluded temper that embrittlement i s r e v e r s i b l ea n d t h a tt h ee m b r i t t l e m e n t i s due t od i f f u s i o no ft h et r a m pe l e m e n t s . The e f f e c t of s t r e n g t h l e v e l and s t r u c t u r e was r e a s o n a b l y c l e a r . The q u e n c h e d b a i n i t e - m a r t e n s i t e ) ( and tempered s t e e l had lower t r a n s i t i o nt e m p e r a t u r e st h a nt h es l o w - c o o l e d( f e r r i t e - p e a r l i t e ) s t e e l on the ingle omposition ested. s c t However, a f t e r 20,000-hr. isothermal e m b r i t t l e m e n t a t 875OF thequenchedandtempered s t e e l had e m b r i t t l e d t o the- same l e v e l as theslow-cooled s t e e l whichhadde-embrittled s l i g h t l y . The u n t e m p e r e d h i g h t r e n g t h ) ( s steel, which does not r e p r e s e n tt h et y p i c a ls t r e n g t h l e v e l s of FWHT steels e x c e p t p o s s i b l y i n t h eh e a ta f f e c t e dz o n e , had v e r y h i g h i n i t i a l t r a n s i t i o n t e m p e r a t u r e s b u td e - e m b r i t t l e ds u b s t a n t i a l l ya f t e r2 0 , 0 0 0 - h r . a t 8750F. The e f f e c t ofhighpressurehydrogen(3,500psig) a t 8750F a f t e r 1,000 h r . was mostpronounced inthe.ferrite-pearlitesamplewhich was degraded to hydrogen due the exposure. Bainite samples the in same a u t o c l a v ed i dn o t show a r a d i c a l c h a n g e i n t h e i r p r o p e r t i e s . The Auger E l e c t r o nS p e c t r o s c o p i c (AES), a n a l y s e so ft h ee m b r i t t l e d g r a i nb o u n d a r i e s showed h i g hc o n c e n t r a t i o n so ft h ee m b r i t t l i n ge l e m e n t P and t o a much lesser e x t e n t Sn. I n t e r e s t i n g l y , steels w i t hh i g h c o n t e n t so f A s d i dn o t reveal s e g r e g a t i o no ft h i se l e m e n t .T h i s i n f o r m a t i o ns u p p o r t st h e formof t h ee m b r i t t l e m e n tf a c t o r X = (1OP 5% + + 4Sn + A s ) proposed Bruscato. by [ h l The most s u r p r i s i n gc o n c l u s i o nCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API P U B L * 7 5 7 8 2 W 0 7 3 2 2 7 0 0 0 8 7 5 0 8 3 m fromthe AES s t u d y was t h a t Cu s e g r e g a t e st ot h eg r a i nb o u n d a r i e s .T h i s e f f e c t i s notnormallyfound and t h e r o l e of Cu a t t h eg r a i nb o u n d a r i e s i s f a r from clear. Overall, t h i s programhasservedtoidentifytheprimarytemper e m b r i t t l e m e n t c h a r a c t e r i s t i c s of t h e c o m e r c i a l Cr-Mo p r e s s u r e vessel steels u s e df o rv e s s e lc o n s t r u c t i o n up t oa b o u t 1975. General guide- l i n e s o ft h e material d e g r a d a t i o n f o r i n d u s t r i a l a p p l i c a t i o n s h a v e b e e n deduced. 6 ___COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBLm757 8 2 W 0 7 3 2 2 7 0 0087507 5 W III. PHASE I: STEP-COOLED EMBRITTLEMENT EXPERIMENTS AND MATERIAL CHARACTERIZATION P r i m a r yO b i e c t i v e sf o rP h a s e I Phase I r e p r e s e n t e d t h e p r i m a r y c h a r a c t e r i z a t i o n o f t h e s u p p l i e d s t e e l samples. The c h a r a c t e r i z a t i o nc o n s i s t e d of ( iM e t a l l o g r a p h i s t r u c t u r e ) c (ii) AST" g r a i ns i z e (iii) Rockwell B Hardness ( i vT e n s i l p r o p e r t i e s ) e (a) O. 2% y i e l d s t r e n g t h (b) Ultimate t e n s i l e t r e n g t h s (c) R e d u c t i o nn i area (cl) Elongation ( v )A n a l y t i c a lc h e m i s t r yw h i c hc o n s i s t so fa n a l y s e sf o r C, Cr, Mo, Mn, S i , N i , Cu, P, S , Sn, Sb, O, N, A s . (vi) The g e n e r a t i o n of Charpyimpactcurvesofunembrittledand step-cooledtemperembrittledsamplesyielding ( a ) FATTU; 40 f t - l b TTU ( b ) FATTE; 40 f t - l b TTE ( c ) AFATT ( o r amount of e m b r i t t l e m e n t , FATTU - FATTE) ( d ) AT(40) ( o re m b r i t t l e m e n tj u d g e d by s h i f t i n 40 f t - l b t r a n s i t i o nt e m p e r a t u r e ) . Material Kev The s a m p l e s l i s t e d a c c o r d i n g t o t h e material key are as f o l l o w s : ( see page 1) 7COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*759 8 2 m 0 7 3 2 2 7 0 00875LO L W ~~ ~ ~~ ~ ~ Material Key Sample Number ___- 1 PLA 2, 0, 2, 0 5 5 6 2 PLA 1, 7 ,1 2 ,1 3 ,1 4 ,3 3 ,3 6 ,4 5 ,4 6 ,4 7 , 48, 4, 5, 0, 1, 2, 4, 5 5 5 7 7 7 7 7 3 PLA 64 1 FOR 77 2 FOR 9 , 1 0 , 1 5 ,5 6 ,5 7 ,5 8 ,5 9 ,7 8 3 FOR 61 1 SAW 4 2 SAW 1 8 ,1 9 ,2 0 ,2 1 ,2 2 ,2 3 ,2 4 ,2 5 ,3 4 , 353738394041 , , , , , 3 SAW 65 2 ESW 8., 1 6 2 6 2 7 7 6 , , , 2 SMA 63, 7, 8, 9 6 6 6 3 SMA 66 Metallography M e t a l l o g r a p h i cs e c t i o n s were prepared from eachsampleand e t c h e d so as t o show t h e p r i o r a u s t e n i t i c g r a i n s i z e and s t r u c t u r e . Photographs were t a k e n a t X200 and X500, two t y p i c a le x a m p l e s are shown i nF i g u r e s 1 and 2. The s t r u c t u r e of each sample i s l i s t e di nT a b l e 1. ASTM G r a i nS i z e( T a b l e 1) The ASTM g r a i n s i z e was judgedbycomparisonwithstandard chartseitherdirectly on t h e m i c r o s c o p e o r bycomparisonwiththe photographs. The e r r o ri nt h e s ed e t e r m i n a t i o n s i s about +1 i n ASTM g r a i n s i z e (ASTM E112-74 P l a t e 1). 8 . " ;""-COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLU757 82 m 0 7 3 2 2 7 0 0087511 3 m T e n s i l eP r o p e r t i e s( T a b l e 1) The t e n s i l e p r o p e r t i e s were judgedfromonetensile. test oneach sample. the In forged and p l a t e material t h et e n s i l es p e c i m e n s were s t a n d a r d 0.505 inches diameter gauge as shown i nF i g u r e 3 , t y p e 1 . The l o n g i t u d i n a l axes ofthesespecimens were p a r a l l e l t o t h e r o l l i n g d i r e c - t i o ni nt h ep l a t e .T r a n s v e r s et e n s i l es a m p l e s were taken from t h e weldments. A s t a n d a r dt e n s i l ec o u l dn o tb et a k e n from most of t h e weld s a m p l e sw i t h o u ti n c l u d i n gt h eh e a ta f f e c t e dz o n e (HAZ) w i t h i nt h eg a u g e l e n g t h .S i n c et h eb a s ep l a t eo r HAZ c o u l dp o s s i b l yy i e l dp r i o rt ot h e weld material, i t was decidedtousereducedsizesampleswhichincluded only weld metal w i t h i nt h eg a u g el e n g t h .T h u s ,t h et e n s i l ed a t ap r o - ducedforweldsamples r e l a t e s s o l e l y t o t h e w e l d .S i n c et h eg r a i ns i z e i s s u f f i c i e n t l y small i ne a c hs a m p l e ,g r a i ns i z ee f f e c t s on t h e t e n s i l e p r o p e r t i e ss h o u l db en e g l i g i b l e .( T h ee f f e c to fg r a i ns i z e on t e n s i l e p r o p e r t i e s i s o n l ya p p a r e n ti ft h e r e are less thanabout 5 g r a i n s i n a c r o s ss e c t i o n ) . A diagramofthetensilesamplesused i s g i v e ni n F i g u r e 3. The s i z e o ft h e weld t e n s i l es a m p l e s i s as f o l l o w s : ___ Tensile SpecimenType Sample No. from Fig. 36 4 3 8 3 16 3 34 4 35 3 37 3 38 4 39 3 40 3 41 3 42 3 43 3 44 3 67 2 68 2 69 2 76 2 -COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm959 8 2 3 2 2 7 0 8 7 5 3 2 07 00 5 Rockwell B hardnessmeasurements were a l s o t a k e n on eachsample(Table 1). A n a l y t i c a lC h e m i s t r y( T a b l e 2) The a n a l y t i c a l c h e m i s t r y was donebythefollowingtechniques: C LECO - Combustion - I R D e t e c t i o n S ( I R Infra-Red) O LECO - HighTemperature Fusion Thermal - Conductometric N (LECO i s a t r a d e name) Cr M o E S ii s sSo n c t r o m e t e r m i pe Cu Ni M n P As Phosphor-Molybdate Technique Sn Sb The l a t t e r fourtrampelements were e v a l u a t e d a t WestinghouseResearch Center and t h e rest were e v a l u a t e d a t Lukens S t e e lR e s e a r c h . It s h o u l db en o t e dt h a tt h et a b l e sg i v et h r e es i g n i f i c a n t f i g u r e s ,w h e r e a si nf a c t ,t h ee r r o ri nm o s t i s s u c ht h a t only two s i g n i f i c a n t f i g u r e s are warranted. S p e c i f i c a l l yt h ec l a i m e dp r e c i s i o n i s as f o l l o w s ( p p means partspermillion): Element C S 2 .002% k Precision 3 ppm FIl ” . E l emen t Cu Ni - i- .01% L- Precision .01% ~____ O N Cr -I 5 ppm ? 3 ppm i- .05% iIl Mn As Sb +- .01% F 10% i- 5% Mo i- .08% Sn 2 5% Si F .01% 1 P 4 5 ppm o r b e t t e r 10 .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 M 0 7 3 2 2 7 0 O Ö B 7 5 1 3 7 W Also i t s h o u l db en o t e dt h a tt h ea n a l y s e sf o rs a m p l e s 1 2 , 13 and 1 4 showed a s i g n i f i c a n t v a r i a t i o n i n M as f o l l o w s : n S amp l e M ( s i t e A) n M ( s i t e B) n 12 .67 .42 13 .,59 .39 14 .53 37 Thequotedvalues of M i n t h e t a b l e s n are theaverageoftheabove estimates: CharpyImpact Data ( T a b l e 3 ) The d a t a g e n e r a t e d f o r t h i s r e p o r t stemmed from two s o u r c e s : (1) WestinghouseResearch on S a m p l e sn o th i t h e r t oe v a l u a t e da n d ( 2 ) samples evaluated a t t h ev a r i o u ss u p p l i e r s l a b o r a t o r i e s . In o r d e r t or e d u c et h et o t a ls c o p e and expense of t h ep r o g r a m ,t h ed a t as u p p l i e d b yv a r i o u ss o u r c e s was a c c e p t e da n dt h er e m a i n i n gd a t ag e n e r a t e d at Westinghouse Research Centér. Since standard the step-cooled emhrittle- menttreatment,termedthe SOCAL step-cooledembrittlement,hasbeen used i n t h e API i n d u s t r y , v i z : 1100°F - 1 h r Cool a t 10°F/hr 1000°F - 1 5 h r Cool a t 10"F/hr 975°F - 24 h r Cool a t 10"F/hr 925°F - 60 h r Cool a t 5"F/hr 865°F - 100 h r Cool a t 5 0 " F / htro 600°F - a i r c o o l T h i se m b r i t t l e m e n tt r e a t m e n t was u s e dt h r o u g h o u tt h e series. D i s c u s s i o n ofPhase I Data A a t t e m p tt of i ta ne q u a t i o nt ot h ed a t ag e n e r a t e di nP h a s e n I was c a r r i e do u tu s i n gr e g r e s s i o na n a l y s i st e c h n i q u e s .U n f o r t u n a t e l y , t h e d i s t r i b u t i o n of e l e m e n t s ,g r a i ns i z e s and s t r e n g t h l e v e l s among t h e set was s u c ht h a t no s p e c i f i cm a j o rt r e n do rc o e f f i c i e n t sa s s o c i a t e dCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • w i t he a c hv a r i a b l ec o u l db ef o u n d . At f i r s ts i g h tt h i s is surprising, s i n c et h e r ea p p e a r st ob e a s u f f i c i e n tr a n g eo fe a c hv a r i a b l ew i t h i nt h e number samples of taken. However, a s t a t i s t i c a l l yd e s i g n e de x p e r i m e n t f o r 14 e l e m e n t sp l u sg r a i ns i z e and s t r e n g t h , i.e. 16 v a r i a b l e s would r e q u i r ec o n s i d e r a b l y more t h a nt h e 6 5s a m p l e sa v a i l a b l e .M o r e o v e r ,t h e v a r i a b l e s would b ea r r a n g e da c c o r d i n gt ot h ed e s i g nr a t h e rt h a nt a k e n at random. Consequently, i t was n o tp o s s i b l et of i n d a f i t t e de q u a t i o nt o thePhase I d a t a f o r two r e a s o n s , v i z . i n s u f f i c i e n t d a t a and u n f o r t u n a t e o r g a n i z a t i o n of t h ev a r i a b l e s . The c o r r e l a t i o nb e t w e e nt h eo f t e n employed "J-factor and AT ( 4 0 ) , shown i n Fig. 4 ( a ) , i s r e l a t i v e l yp o o r forbothplate andweld metal. The datacan,however,beexpressedintheformofthehisto- grams and a few u s e f u lo b s e r v a t i o n s made. The histograms are shown i n F i g u r e s 5 through 18. The u p p e rh i s t o g r a mi ne a c ho ft h e s ef i g u r e s r e p r e s e n t s a l l t h e weld and p l a t e and forgedsamples,whereastheweld metal c o n t r i b u t i o n a l o n e i s r e p r e s e n t e d by t h eh a t c h e d areas w i t h i n t h e t o t a lh i s t o g r a m . The dashed curves are a na p p r o x i m a t i o nt ot h es h a p eo f t h eh i s t o g r a mf o rt h ep l a t e a n df o r g e ds a m p l e sa n ds i m i l a r l yt h es o l i d c u r v er e p r e s e n t st h ew e l d s .T h u s , a comparison of weld and p l a t ep l u s forgedsamplecharacteristicscanbe made withineachhistogram. There i s a q u e s t i o n of how well t h eh i s t o g r a m sr e p r e s e n tt h e Cr-Mo A387 s t e e l s . The samples were drawn from many s o u r c e s , some of which were from a c t u a l p r e s s u r e v e s s e l s and o t h e r s from h e a t s o r weld- mentsproducedtosimulatethenormalvessel steels. A few of t h e samples were includedintheprogrambecausethey were " i n t e r e s t i n g " i n t h a t t h e y hadanomalouslyhightemperembrittlementfractureappearance t r a n s i t i o nt e m p e r a t u r e ( F A T T ~ ) o rr e p r e s e n t e d some extreme i n composi- tion.Thesesamplesmightput a b i a s on theaccumulateddataandhence i nt h i sr e s p e c tt h eh i s t o g r a m s may n o t t r u l y r e p r e s e n t t h e class of s t e e l . However, t h e r e are s u f f i c i e n t a m p l e s h a t h e i s t o g r a m s h o u l d s t t h s g i v e a r e a s o n a b l ea p p r o x i m a t i o nt ot h en o r m a lc h a r a c t e r i s t i c s . F i g u r e s 5, 6 and 7 show t h e FATT d a t a . The FATTU ( u n e m b r i t t l e d ) and FATTE ( e m b r i t t l e d ) show t h a t as a class t h e weld have a h i g h e r FATT t h a nt h ep l a t ea n df o r g i n g s .B o t h FATTE and AFATT, due t o temper e m b r i t t l e m e n t ,r e v e a lt h a tc e r t a i n 2 1 / 4 C - 1Mo submerged arc weld- r ments (2 SAW) h a v ep o o r e re m b r i t t l e m e n tc h a r a c t e r i s t i c st h a nt h e rest. Overall,onecanconcludethatweld may bemorepronetoembrittlement and may have a h i g h e r u n e m b r i t t l e d FATTU t h a n t h e p l a t e andforged material. F i g u r e s 8 through 1 7 show t h e d i s t r i b u t i o n o f mostof t h e ele- m e n t si nt h e s t e e l s . F i g u r e s 8, 9 and 10 show s i g n i f i c a n td i f f e r e n c e s between weld the metal and p l a t e a n df o r g i n g sf o r C , M and S i . n In g e n e r a l ,h i g h e rl e v e l s of M and S i l e a dt oh i g h e r n FATT v a l u e s i n t h e presence of P. [4,5,61COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*759 8 2 m 0732270 087515 0 O m P, With regard to the tramp elements, Sn, As and Sb, Figures 11 through 1 4 , little difference is found between weld metal and plate for P and As, whereas plate and forgings exhibit a higher content of Sn and Sb. A secondary high peak in is associated with2 SAW samples. This P again confirms the secondary-highAFATT peak in Figure 7 for 2 SAW materials. (See page 8 for sample numbers) The histogram for does not indicate a specific trend, whereas S the histograms for and O, Figures 16 and 17, show very much higher N It concentrations of these elements for the welds. is interesting to (ESW) samples exhibit the lowest oxygen note that the electroslag weld on temper content of the weld class. The role of these two elements embrittlement is not known. The J embrittlement factor(Mn + Si) x (P + Sn) x lo4 does not show a strong difference between plate and weld metal, even though it is not intended to be used for welds. Interestingly, the ESW samples all fall in the 50-100 range. If they were taken out of the weld set, then the weld metal would show a greater population to 250 compared 200 at with 100 to 150 for the plate and forgings (Figure18). Even though the histograms show reasonable correlations between the FATT data and compositions, especially Si and P and C, any Mn, interpretation of the trends must be treated with caution. Simple plots of FATT~, FATT~or FATT versus - of the compositional elements or one any the J embrittlement factor show specific trend whatsoever. This no observation only confirms the fact that the expression for FATT in terms of composition is a complex function which represents the multiple interactions of the primary alloying elements and the tramp elements.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API P U B L * 7 5 7 8 2 W 0 7 3 2 2 9 0 0087516 2 W IV. PHASE II: ISOTHERMAL EMBRITTLEMENT EXPERIMENTS The p r i m a r yo b j e c t i v ei nP h a s e II was t o c h a r a c t e r i z e t h e i s o - thermalembrittlementof 25 s e l e c t e d steels and t ou l t i m a t e l yc o m p a r e t h i sd a t aw i t ht h es t e p - c o o l e de m b r i t t l e m e n t data of Phase I. The i s o t h e r m a le m b r i t t l e m e n tm a t r i x was as f o l l o w s : Temperature (OF) Time ( h r ) [E] 950 x I 11,000 10,000 20,000 The samples were s e l e c t e d on t h eb a s i so f i) Material a v a i l a b i l i t y i i ) Extremes i n t e p - c o o l e d m b r i t t l e m e n t s e i i i ) Extremes i n o m p o s i t i o n a e l e m e n t s c l iv) tructure S and s t r e n g t h l e v e l The p r i m a r yd a t ag a t h e r e d was t h e 40 f t - l b TT and FATT. Wherever p o s s i b l ea ni n d i c a t i o no ft h eu p p e rs h e l fv a l u e was a l s oo b t a i n e d . The b a s i cd a t ag a t h e r e d i s g i v e ni nT a b l e s 4 through12. F i g u r e s 19 through 43 show t h e 40 f t - l b TT and FATT p l o t t e d as a f u n c t i o n of t h e isothg.rpa-X..embrittlementtemperaturefor 1,000, 10,000 and 20,000 h r . For r g f e r e z i e ,t h ëu n e m b r i t t l e d (U) and step-cooled e m b r i t t l e d ( E ) t r a n s i t i o n . t e m p e r a t u r e s are i n d i c a t e d bybenchmarks in t h e same figures. Samples tested with- Phase II o r i e n t a t i o n are i n d i - c a t e dw i t ha na s t e r i s ki nT a b l e 3. F u r t h e rd a t a i s g i v e ni nT a b l e1 6 where t h ee f f e c t o fs p e c i m e no r i e n t a t - i o n i s shown. The s u p p l i e dd a t a f o r sample 26 (Table 3 ) was p r o b a b l y i n c q r r e c t and thebenchmark U r e p r e s e n t sa ni n d e p e n d e n t test. Where T and E d a t af o rt h eP h a s e I II s p e c i m e no r i e n t a t i o n were n o ta v a i l a b l e ,P h a s e I d a t aa d j u s t e da c c o r d i n g t ot h er e l a t i o n s h i pg i v e ni nS e c t i o n V I below were used. F o rt h es a m p l e sw h i c he x h i b i td i s t i n c te m b r i t t l e m e n t( o r i n c r e a s ei nt h et r a n s i t i o nt e m p e r a t u r e ) ,t h e maximum e f f e c t i s i n t h e r a n g e 8000F t o 9500F. (See igures F 19 t o 4 3 ) Histograms of t h e 40 f t - l b TT i nt h eu n e m b r i t t l e d and s t e p - c o o l e de m b r i t t l e dc o n d i t i o n s are compared w i t h t h e maximum embrittlernentCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLa957 A2 W 0 7 3 2 2 9 0 0 0 8 7 5 1 7 W after 1,000 and 20,000 hr isothermal embrittlement in Fig. 4 4 . These histograms give a clear indication of the general trend of embrittlement after long term isothermal exposure.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services ,
  • V. THE EFFECT OF DE-EMBRITTLEMENT Samplesreceivedfromvarioussources had r e c e i v e d a number of d i f f e r e n th e a tt r e a t m e n t si n c l u d i n g a r a n g e of p o s t - w e l dh e a tt r e a t m e n t s (PWHT) . InPhase I thesesamples were t e s t e di nt h e" a s - r e c e i v e d " c o n d i t i o nw h i c h was t e r m e dt h e" u n e m b r i t t l e d "c o n d i t i o n . The F r a c t u r e A p p e a r a n c eT r a n s i t i o nT e m p e r a t u r ef o rt h i sc o n d i t i o n was a b b r e v i a t e dt o FATTU, w h e r et h es u b s c r i p t U d e s i g n a t e s" u n e m b r i t t l e d . "I nf a c t , due t o t h e slow c o o l i n gt h r o u g ht h et e m p e re m b r i t t l e r n e n tr a n g e ,v a r i o u sd e g r e e s oftemperembrittlementmight well havebeenexperienced by each sample i nt h i sc o n d i t i o n . The same samples were s u b j e c t e dt ot h e SOCAJ, Step- Cooled Temper F m b r i t t l e m e n tt r e a t m e n ta n dg i v e nt h ed e s i g n a t i o n E. (See Page 11) It was t h o u g h tt h a tt h ep o s s i b l ec o r r e l a t i o n sb e t w e e ns a m p l e c h a r a c t e r i s t i c s( s t r u c t u r e ,y i e l ds t r e n g t h and composition) and t h e degreeoftemperembrittlement wouldbe b e t t e r r e v e a l e d by comparisonof t h e E c o n d i t i o nw i t hs a m p l e si n a d e - e m b r i t t l e dc o n d i t i o n .S a m p l e s were d e - e m b r i t t l e d by h e a t t r e a t i n g a t llOOoF f o r 2 h r and water quenching. T h i sc o n d i t i o n i s g i v e nt h ed e s i g n a t i o n D. Thus, - a number of samples h a v eb e e nt e s t e di nt h r e ec o n d i t i o n s . U - Unknown degreeofembrittlementoras-received E - Step-cooledembrittlement from c o n d i t i o n U D - D e - e m b r i t t l e dc o n d i t i o nf r o mc o n d i t i o n U In Phase I, AFATT was d e f i n e d as F A T T E - ~ ~a~ ~ sU m i l a r l y t h e nd i change i n t h e 40 f t - l b TT was AT(40) = T ( 4 0 ) E - T(40)~- The d a t a fromPhase I a n dt h ec u r r e n t t e s t s are g i v e n i n T a b l e s 13, 14 15. and S i n c et h e U c o n d i t i o nm i g h tb es l i g h t l yt e m p e re m b r i t t l e d ,o n e shouldexpectthe FATTU and T ( 4 0 ) ~ t o b e g r e a t e r t h a n FATTD and T ( 4 0 ) ~ and less t h a n PATTE a n dT ( 4 0 ) ~ ,r e s p e c t i v e l y .I n s p e c t i o n of T a b l e s 13 and 14 shows t h a t i n g e n e r a l t h i s i s n o tt h e case. I n o r d e r t o e x p l o r et h er e a s o nf o rt h e many d i s c r e p a n c i e s i n t h e d a t a ,t h ec u r v e s of t h e D, U and E c o n d i t i o n were compared. I nn e a r l y e v e r yi n s t a n c e ,t h eu p p e rs h e l f of D > U > E as i s alsoobviousfrom Table PS. Thus on e m b r i t t l e m e n tt h ec u r v e s are d e f i n i t e l y changed i n t h eu p p e rs h e l fo r 100% d u c t i l er e g i o n . Also t h eg r a d i e n to ft h eC h a r p y c u r v e s becomes less s t e e pw i t he m b r i t t l e m e n t .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 82 W 0732270 087519 0 B m Data similar t ot h ea b o v e was found f o r 3.5Ni-Cr-Mo-V rotor s t e e l by D r . J. Watanabe. L61 He p o i n t e d u t h a t n t e r g r a n u l a r o i f r a c t u r ee x t e n d st ol o w e rt e m p e r a t u r e s as thedegreeoftemper embrittlementncreased. i It i s r e a s o n a b l et os u g g e s tt h a tt h e i n t r o d u c t i o no fa ne x t r a mode o f f r a c t u r e , i.e., i n t e r g r a n u l a rf r a c t u r e by temperemhrittlement, serves a l s ot oc h a n g et h eg r a d i e n t so ft h e Charpy curves. A. S. Tetelman and A. J. McEvily, Jr. r71 p o i n to u tt h a t t h e Charpycurvegradient is difficulttodefine anddependsstronglyon m i c r o s t r u c t u r a lv a r i a b l e s . They s t a t e t h a t i n g e n e r a l a processwhich l o w e r st h eu p p e rs h e l fv a l u e w i l l t e n dt ob r o a d e no u tt h e 100% d - u c t i l e - t o - b r i t t l er a n g e( o rc h a n g et h e Charpycurveslopeto a l o w e rg r a d i e n t ) . It f o l l o w s from t h i ss t u d yt h a tt h er e l a t i o n s h i pb e t w e e nt h e (D) and (U) c o n d i t i o n i s f a r from simple.Consequently a c l a r i f i c a t i o n of t h ea m b i g u i t yi nt h ed a t ac a u s e d by v a r i a b l e d e g r e e s o f e m b r i t t l e m e n t stemming from a r a n g eo fc o o l i n g rates i s n o t p o s s i b l e .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 0732290 87520 00 4-1 VI. THE EFFECT OF SPECIMEN NOTCH ORIENTATION The two s p e c i m e nn o t c ho r i e n t a t i o n su s e di nt h i s program are shown i n F i g u r e 45. In Phase I o ft h ep r o g r a m ,t h eo r i e n t a t i o no ft h e notch was p a r a l l e l t o t h e p l a t e o r weld s u r f a c e ,d e s i g n a t e d L-S and T-S, r e s p e c t i v e l y ,w h e r e a si nP h a s e II t h en o t c h *ras p e r p e n d i c u l a rt ot h e s u r f a c e , L-T and T-L, r e s p e c t i v e l y . In ordertocomparePhase I andPhase II d a t a , a comparative study was c a r r i e d o u t on a fewsamplesfromwhich s u f f i c i e n t material was a v a i l a b l e . The d a t af o rt h eP h a s e II u n e m b r i t t l e d (U) and s t e p - c o o l e de m b r i t t l e d( E )c o n d i t i o n was d e r i v e d from o n l yf i v es p e c i m e n sp e r Charpy curve. Some of t h ed a t a was s c a t t e r e dt o a p o i n tt h a t estimates of t r a n s i t i o nt e m p e r a t u r ec o u l do n l yb e made t o k500F (Table 1 6 ) . A p l o t of t h i s d a t a , i n w h i c h t h e p o o r e r estimates havebeenomitted, is shown i n F i g u r e 46. The e r r o rb a n d s ,r e p r e s e n t e d by b a r s and c i r c l e s , h a v eb e e ni n c l u d e di no r d e rt og i v e a c l e a r r e p r e s e n t a t i o n of. t h e comparativeexperiment. A l e a s t s q u a r e sa n a l y s i so ft h ed a t ay i e l d e dt h ee x p r e s s i o n ( i n OF) (Phase I d a t a ) = O. 96 (Phase II d a t a ) - 10.5 Eq* (1) w i t h a s t a n d a r d d e v i a t i o n of 25.8 and a correlationcoefficient, r = 0.92. (See page 20 f o rd i s c u s s i o no f r) By eye i t would a p p e a rt h a t (Phase I d a t a ) = (Phase II d a t a ) - IOOP, +25OF. W * (la) Based upon t h i ss t u d y , i t i s p o s s i b l et oa d j u s tP h a s e I orientationdatatothat of Phase II byadding lOoF t o t h e FATT o r 40 f t - l b TT. In t h i s way, w h e r et h ed i r e c tm e a s u r e m e n t s were not made, t h e step-cooledembrittlementdataofPhase I canbe compared w i t h t h e isothermal mbrittlement ata e d of Phase II. O v e r a l lt h e r e is l i t t l e c h a n g ei nt h ed a t ad u et ot h ec h a n g ei no r i e n t a t i o n shown i n F i g u r e 45. 18 , 7 " - "- - - - - " - "COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*’759 8 2 W 0 7 3 2 2 ’ 7 0 0 8 7 5 2 1 0 b W VII. PREDICTION OF LONG-TERM ISOTHERMAI, EMBRITTLEMENT The prediction of long-term service embrittlement of pressure vessel steels is of considerable importance. Consequently various methods of assessing potential embrittlement have been employed; the main ones being the step-cooled embrittlement screening test and correlations with composition. The API program allows for the comparison of these correlations with isothermal embrittlement up to 20,000 hr. There are two models (often referred to as embrittlement fac- tors) in the literature which relate temper embrittlement to composition in 21 / 4 Cr - 1 Mo steels. The first by Bruscato, primarily for weld L41 metal, delineated high and low embrittlement areas on a two dimensional plot of (Mn+ Si) and ii = (10 P + 5 Sb + 4 Sn + As)/100. Recognizing that the iso-embrittlement curves in this plot arê approximately hyperbolic, the embrittlement can be represented by a function of the fo m ATT = fl [ E (Mn + S) i] where ATT stands for the shift in the transition temperature. Thesecondmodel,byMurakami,etisprimarilyforplate material and is given by ATT = f2 [ (P + Sn) (Mn + Si) x lo4] which is similar in form to that of Bruscato. The function is f2 usually called the J-factor. Two of the most commonly used predictive methods have been examined in this section: the SOCAL step-cooled embrittlement screening test and the J-factor. There is greater scatter (or subjectivity) in the FATT data, therefore, the 40 f t-lb data has been used for the analysis. The TT basic data, extracted from previous tables, is given in Table All 17. II of this data is for the Phase orientation. U are shown in The values used for the unembrittled condition Figures 19 to 43 (Section I ) V. The maximum amount of isothermal embrittlement, which usually occurred in the range 800-950°F, was used in the analysis. The equations derived therefore yield predictions for 19COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLr959 8 2 m 0732270 0087522 8 6 a na p p r o x i m a t i o nt ot h e maximum embrittlementfoundinthetemper e m b r i t t l e m e n tr a n g e and n o tt o a s p e c i f i ci s o t h e r m a le m b r i t t l e m e n t temperature. S i n c et h e r e i s scatter i n t h e 40 f t l b d a t a , t h e b e s t a p p r o a c h t ot h ec o m p a r i s o no ft h ei s o t h e r m a le m b r i t t l e m e n tw i t ht h es t e p - c o o l e d o rJ - f a c t o rm e a s u r e m e n t s i s via a l e a s t - s q u a r e sf i t t e de q u a t i o n .I nt h e a n a l y s i so ft h ed i f f e r e n c e sb e t w e e nt h e two o r i e n t a t i o n sa b o v e , i t was n o t e dt h a tt h es t a n d a r dd e v i a t i o n was about 250F. In a studyof d i f f e r e n c e sb e t w e e nt h e s em e a s u r e m e n t s ,t h es t a n d a r dd e v i a t i o ns h o u l db e 25 x fi o a p p r o x i m a t e l y r 36OF. The r e g r e s s i o n a n a l y s i s l e a d s t o a model o r a n e x p r e s s i o n r e l a t i n gt h ed e p e n d e n tv a r i a b l e( e . g . , AFATT) t o terms which are i n d e p e n d e n tv a r i a b l e so rc o m b i n a t i o n so ft h ei n d e p e n d e n tv a r i a b l e s .F o r example, a q u a d r a t i cm o d e li n c l u d e s terms such as Mo, C r 2 , C C r , MnP, e t c . One m e a s u r eo ft h eq u a l i t yo ft h em o d e l is t h ec o r r e l a t i o n c o e f f i c i e n t b e t w e e nt h eo b s e r v a t i o n and t h e m o d e l p r e d i c t i o n , s i g n i f i e d by r , which l i e s between O and 1. I f r < .S, t h e model i s u s u a l l y c o n s i d e r e dt ob eq u i t ep o o r , i .e., t h e p r e d i c t i o n s of t h e model are not c l o s e l yr e p r e s e n t a t i v eo ft h eo b s e r v a t i o n s . A s r approaches 1, t h e p r e d i c t i o n s are c l o s et ot h eo b s e r v a t i o n s . However, t h e number of terms i n c l u d e di nt h e m o d e ls h o u l db es i g n i f i c a n t l y less t h a nt h e number of o b s e r v a t i o n st oe n s u r et h a tt h e model i s meaningful. The r e g r e s s i o n a n a l y s e s y i e l d e d t h e f o l l o w i n g e q u a t i o n s : I I f Standardlation .Cor e F iq ue d i o n E tt at (F) C o e f f i ce e na t i o n D i vi t (F) bT(40)E-U = -1.7 + .72AT(40)1,000-U .57 34 AT(40)E-U = .34 + .50AT(40)10,000-U .57 34 AT(40)E-U = -1.5 + .44AT(40)20,000-U .57 34 J = 142 + .80AT(40)1,000-U .39 57 J = 131 -t .70AT(40)10,000~u .-52 54 J = 145 + .45AT(40)20,000-U .35 J = 148 i .9AT(40)E-U - .62 where t h en o t a t i o n A ~ ( 4 0 ) ~ s- a n d sf o rt h ec h a n g ei nt h et r a n s i t i o n t~ t e m p e r a t u r ei nt h eu n e m b r i t t l e dc o n d i t i o n , U t ot h es t e p - c o o l e d e m b r i t t l e dc o n d i t i o n , E, etc. See Key f o r b b r e v i a t i o n s A and Symbols, page iii. 20 - - " - - - "~ ~ - - .. WCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 W 0 7 3 2 2 7 0 0 8 7 5 2 3 0 T m A s bad as these fitted equations are, can be seen that it overall AT(40)E-u has a greater correlation with the isothermal embrittlement than the J-factor, and that the standard deviation is in the range that would be expected for this quality of data. Looking at these expressions in a simplified form, we have approximately (1,000 hr isothermal embrittlement)= 1.4 (Step-Cooled Embrittlement) (10,000 hr isothermal embrittlement)= 2 (Step-Cooled Emhrittlement) (20,000 hr isothermal embrittlement)= 2.3 (Step-Cooled hbrittlement) I can be seen that the coefficient increases with time, as t would be expected. Also the step-cooled embrittlement is (on thé average, as represented hy this method) less than the isothermal embrittlement. A least-squares fitted equation to thë coefficients versus g lo (isothermal embrittlement time) yielded log (isothermal embrittlement time) = .91 + 1.5 (Coefficient) Eq. (3) withastandarddeviationof .O66 and a correlation coefficient= .995 It follows.thenthat very approximately the isothermal embrittlement after time hr can be expressed by t I t) ( = -67 (logl"(t) - 091) X (S*C*E*) Eq. (4) where I t stands for isothermal embrittlement and S.C.E. stands for the () step-cooled emhrittlement. Interestingly, the time required for the isothermal enbrittle- ment to equal the step-cooled emhrittlement, from Eq. 4 ) , is approxi- ( mately 250 h r . This is roughly comparable with the total embrittlement time (200 hr) used in the step-cooled emhrittlement procedure. Equation 4 also leads to the conclusion that years of in-service embrittlement 30 is about equal to three times the step-cooled. embrittlement. 21COPYRIGHT American Petroleum Institute K -Licensed by Information Handling Services
  • A P I PUBLU757 82 M 0732270 087524 0 L m VIII. THE EFFECT OF REPEATED DE-EMRRITTLEMENT ON ISOTHERMAL EMRRITTLEMENT AT 8750F The s e l e c t e ds a m p l e s ,n o s . 18 and 38, were exposedto a series o ft h e r m a lc y c l e s and a blankofeach steel t a k e n f o r t e s t i n g a t each s t a g e . The t h e r m a lc y c l e s ,t h eF r a c t u r eA p p e a r a n c eT r a n s i t i o n Tempera- t u r e (FATT) and 40 f t - l bT r a n s i t i o nT e m p e r a t u r e s ( 4 0 f t - l b TT) asso- ciatedwitheachstage are g i v e n i n T a b l e 18. The FATT and t h e 40 f t - l b . T T were t h e same f o re a c h s t e e l a f t e r t h ed e - e m b r i t t l e m e n ts t a g e (1 and 4 i nT a b l e 18). S i m i l a r l yt h et r a n s i - t i o nt e m p e r a t u r e sa f t e r1 0 0 0 - h ri s o t h e r m a le m b r i t t l e m e n t a t 8750F were t h e same ( s t a g e s 2 and 7 i nT a b l e 18). A f t e r 5000-hr i s o t h e r m a l emhrittlementsample 38 had n o tc h a n g e ds i g n i f i c a n t l y from the1000-hr s t a g e . However, sample 28, a f t e r 5000 h r , showed a ni n c r e a s e from t h e 1000-hr t r a n s i t i o nt e m p e r a t u r e sa f t e rt h es e c o n dd e - e m b r i t t l e m e n ts t a g e and a r e d u c t i o na f t e rt h et h i r dd e - e m b r i t t l e m e n ts t a g e . It i s implied t h e r e f o r e t h a t temperembrittlement i s r e v e r s i b l e and t h a t t h e e m b r i t t l e m e n t i s due t o t h e d i f f u s i o n ofthetrampelements (P, Sn,Sb, As). The p o s s i b i l i t y of i r r e v e r s i b l e temper embrittlement (irrever- by sible)carbideprecipitation may havebeenprecluded by t h e EJHT of thesesampleswhich was l l O 0 o Ff o r 8 h r + 12000F f o r 1 5 h r + 12750F f o r 7 h r + Cool a t 500F perhour.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 0087525 3 m IX. THE EFFECT OF STRENGTH LEVEL AND STRUCTURE ON TEMPER EMBRITTLEMENT Heat T r e a t m e n ta n dS t r u c t u r e s . T h i ss e c t i o no ft h e API c o n t r a c t r e q u i r e d t h a t t h r e e s t r u c t u r e s , v i z .m a r t e n s i t e ( M ) , b a i n i t e ( R ) , and f e r r i t e - p e a r l i t e (P-P) be tempered from sample one t o t h e same s t r e n g t h l e v e l , a n d t h a t o n e s t r u c t u r e , b a i n i t e ,b et e m p e r e dt ot h r e es t r e n g t hl e v e l s .F i g u r e 47 shows t h e c o n t i n u o u sc o o l i n gt r a n s f o r m a t i o nd i a g r a mf o ra n A387D s t e e l w i t h a compositionvery similar t o t h a t of sample 7.5, which was a s s i g n e dt o t h i s s t u d y . 181 It was r e l a t i v e l y d i f f i c u l t t o p r o d u c e t h e t h r e e s t r u c t u r e s at t h e same s t r e n g t hl e v e l . Whereas t h e M o r R s t r u c t u r ec o u l db et e m p e r e d down t o a minimum s t r e n g t h l e v e l correspondingtoRockwell R (RB) of 87, t h e F-P s t r u c t u r e was a l w a y si nt h e RB range of 78-87. The higher s t r e n g t h l e v e l c o r r e s p o n d st o a s h o r t time, two h o u r s , a t 1200°F- F i g u r e 47 shows t h a t t h i s i s s u f f i c i e n t time t oc r o s st h eF i €t r a n s f o r - m a t i o nc u r v ea n dt h em e t a l l o g r a p h i cs e c t i o n shown i n F i g u r e 48 confirms t h a tt h e F-P s t r u c t u r e was formed. The samples were water quenched from 1200OF t og i v et h ee q u i v a l e n tt o a d e - e m b r i t t l e d F-P c o n d i t i o n . Slow c o o l i n gt h r o u g ht h er a n g e 1100OF t o 600OF c o u l d ,o fc o u r s e ,l e a dt o a small degreeoftemperembrittlement. The t r a n s f o r m a t i o n d i a g r a m i n d i c a t e s t h a t b a i n i t e i s formed a t a l l quenching rates. I no r d e rt o form m a r t e n s i t e ,t h eb l a n k s( 0 . 5 x 2 x 4 . 5i n . ) were q u e n c h e df r o mt h ea u s t e n i t i z i n gt e m p e r a t u r eo f 17000F i n t o s t i r r e d wat-er. The p e r c e n t a g e of b a i n i t e formed i nt h i sp r o c e s ss h o u l d b e q u i t e small buthasnotbeendetermined.There is l i t t l e d i f f e r e n c e b e t w e e nt h em e t a l l o g r a p h i cs e c t i o n so f what w l l l be r e f e r r e d t o as t h e "quenchedbainite-martensite (QBM) and t h eb a i n i t e( F i g u r e4 9 ) . The b a i n i t e s t r u c t u r e was formedbyforced a i r c o o l i n gt h e samplefrom 1700OF t o 9500Fandholding a t 950°F f o r onehour(3.6 x lo3,) a t which p o i n tt h et r a n s f o r m a t i o n i s complete. The c o o l i n g rate was a r r a n g e di ns u c h a way thatthesamplesurfaceremainedabove 950°F (í.e., abovethe M temperature of 869OF) w h i l et h ec e n t e ro ft h es a m p l e , c o o l e dt o 950°F f a s t e n o u g hn o tt o form f e r r i t e . A f t e r 67 h r a t 12750, t h eb a i n i t es t r u c t u r e had t h e same s t r e n g t h l e v e l , RB = 87, as i t had a f t e r 24 h r .T h i sa p p e a r st ob et h el o w e rs t r e n g t hl e v e lf o rt h i s p a r t i c u l a r sample with a b a i n i t i cs t r u c t u r ea n d ,c o i n c i d e n t l y , it i s e x a c t l yt h e same as t h es t a r t i n gc o n d i t i o n . It was, t h e r e f o r e ,d e c i d e d t ou s et h e" a s - r e c e i v e d material f o r t h e l o w e r s t r e n g t h b a i n i t i c sample. A = 98 was o b t a i n e d by tempering a t 1275F f o r 4 h r . TheCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • -~"" A P I PUBL*959 82 m 0732290 08752b 0 5 upperstrengthlevel was o b t a i n e d by u s i n g t h e material i n anuntempered c o n d i t i o n (RB = 108)- The h i g h a n d l o w s t r e n g t h b a i n i t e s a m p l e s . were de-embrittled p r i o rt ot e s t i n g . Thus a l l the samples were i n a d e - e m b r i t t l e ds t a r t i n g condition. able 9 ives he omplete eat reatments. T 1g t c h Threespecimenblanks i ne a c ho ft h ef i v ec o n d i t i o n s were placed i n a f u r n a c e a t 8750F, t h et e m p e r a t u r ed e s i g n a t e d as TM4 e a r l i e r program. The t h r e e l a n k s b were i s o t h e r m a l l yt e m p e re m b r l t t l e df o r 1,000, 10,000 and 20,000 hr. I s o t h e r m a lE m b r i t t l e m e n tR e s u l t s and D i s c u s s i o n The b a s i c Charpy impact test d a t af o rt h ei s o t h e r m a le m b r i t t l e - m e n to ft h ef i v es a m p l e sf o rt h ed e - e m b r i t t l e d , 1,000, 10,000 and 20,000 h ri s o t h e r m a le m b r i t t l e m e n tc o n d i t i o n s are g i v e ni nT a b l e 20. The 40 f t - l b TT f o r t h e f i v e s a m p l e s i s shown as a f u n c t i o no fi s o t h e r m a l e m b r i t t l e m e n t time i nF i g u r e 50. The t r e n d so ft h e FATT f o rt h e s e samples a r e similar t ot h o s e shown i nF i g . 50. The e f f e c t o f s t r e n g t h l e v e l i n t h e b a i n i t i c s t r u c t u r e is r e a s o n a b l y clear a f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n t . The lower v t h es t r e n g t h level, t h e o w e r h e l t FATT. However, t h e m b r i t t l e m e n t e c h a r a c t e r i s t i c s as a f u n c t i o no f time are a l i t t l e niore complex. The h i g h e s t s t r e n g t h level B(108),which i s a r e - a u s t e n i t i z e d and untempered steel, continuously e-embrittles.d The i n t e r m e d i a t e t r e n g t h l e v e l s steel B(98)appears a t f i r s t t o b es u p e r i o rt ot h el o w e s ts t r e n g t hl e v e l s t e e l B(87). Both s t e e l s e m b r i t t l ew i t h time b u tt h el o w e rs t r e n g t h steel r e l a t i v e l y less t h a nt h ei n t e r m e d i a t e .I f one t a k e si n t o con- s i d e r a t i o n t h e maximum s c a t t e r band, i t c a nb es e e nt h a tt h e r e i s not n e c e s s a r i l y a g r e a td i f f e r e n c eb e t w e e nB ( 8 7 ) and B(98). The e f f e c t o f s t r u c t u r e a t t h eo n es t r e n g t hl e v e l( R o c k w e l l B Hardness f 7) an lso e l-early een n ig. o8 c a b c s i F 50. The f e r r i t e - p e a r l i t es t r u c t u r e ,F P ( 8 7 ) ,h a s a t r a n s i t i o nt e m p e r a t u r eo v e r 1500F g r e a t e rt h a nt h eo t h e r two i nt h ed e - e m b r i t t l e dc o n d i t i o n . It de- embrittlesslightlybutinrealitychangesvery l i t t l e a f t e r 1000-hr isothermal mbrittlementIn ontrasthe uenched tructure e . c q s r e p r e s e n t i n g m a r t e n s i t e , QBM(87), s t a r t s a t a r e l a t i v e l y v e r y low de- e m b r i t t l e dc o n d i t i o nb u tc o n t i n u o u s l ye m b r i t t l e s with time t oa l m o s tt h e same l e v e l as the FP(87) sample. The e m b r i t t l e m e n tc h a r a c t e r i s t i c so f QBM(87) are a l m o s ti d e n t i c a lt ot h o s e of B(98). The c o n c l u s i o n s from t h e s t r u c t u r e s t u d y are t h a tf o rs a m p l e 75 t h ef e r r i t e - p e a r l i t es t r u c t u r eh a s a g r e a t e rt r a n s i t i o nt e m p e r a t u r et h a n e i t h e rt h em a r t e n s i t i co rb a i n i t i cs t r u c t u r e s .A f t e r 20,000-hr isother- mal e m b r i t t l e m e n t ,t h em a r t e n s i t i cs t r u c t u r eh a s a t r a n s i t i o n tempera- t u r ec o m p a r a b l ew i t ht h a to ff e r r i t e - p e a r l i t e and s l i g h t l y h i g h e r t h a n t h a t of b a i n i t e . It i s p o s s i b l et h a ts a m p l e sw i t h a d i f f e r e n tc h e m i s t r y may e x h i b i t d i f f e r e n t d e g r e e s o f e m b r i t t l e m e n t f o r e a c h s t r u c t u r e .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • .API P U B L X 7 5 7 8 2 m 0 7 3 2 2 7 00 0 8 7 5 2 7 7 m X. THE SEGREGATION OF ELEMENTS TO GRAIN BOUNDARIES I N Cr-Mo STEELS AFTER 20,000 HR ISOTHERMAT., EMBRITTLEMENT ASSESSED BY AUGER ANALYSIS S e l e c t i o n of Samples f o r AES Study I no r d e rt o select t h es a m p l e sf o rt h e Auger E l e c t r o nS p e c t r o - s c o p i c (AES) s t u d yo fg r a i nb o u n d a r ys e g r e g a t i o n , i t was n e c e s s a r yt o d e t e r m i n ew h i c hs a m p l e sh a da ni n t e r g r a n u l a rf r a c t u r e mode ( I G ) as opposed t oc l e a v a g eo rd i m p l e dr u p t u r e modes (CL and DM). Based on t h e f r a c t o g r a p h i cs t u d y , see Appendix S e c t i o n( b ) ,c a n d i d a t es a m p l e s were chosenand Auger specimens were machinedfrombrokenChar-pyspecimens. The l i s t of t h e s a m p l e s a n d t h e a n a l y t i c a l c h e m i s t r i e s i s g i v e ni nT a b l e 21. E x D e r i m e n t a lR e s u l t s The experimentalprocedureused was i d e n t i c a l t o t h a t d e s c r i b e d by J o s h i and S t e i n . E91 Specimens were broken i n a vacuum of 10-9 t o 10"O t o r r and a s u r f a c e a n a l y s i s was c a r r i e d o u t * u s i n g a 5 vm diameter beam. The beam p o s i t i o n on t h ef r a c t u r es u r f a c e was a d j u s t e dt og i v e a maximum r e a d i n gi n P, t h u si n d i c a t i n g a g r a i nb o u n d a r yp o s i t i o n . The p r o f i l e of t h ec o n c e n t r a t i o no fe l e m e n t sa d j a c e n tt ot h es u r f a c e was o b t a i n e d byremoving t h e s u r f a c e material by i o n s p u t t e r i n g . . The a n a l y s e s were c a r r i e do u t a t d e p t h s of 2 5 , 50, 100, 200, 400, 800 and 1 6 0 0 8 f r o mt h eo r i g i n a lf r a c t u r es u r f a c e s . The f i r s t set of seven samples were broken a t room t e m p e r a t u r e s i n c e t h e i r FATT was a t o ra b o v et h i st e m p e r a t u r e . Post-mortem scanning e l e c t r o nm i c r o s c o p e (SEM)t e v a l u a t i o n s r e v e a l e d t h a t a l l thesamples . f r a c t u r e d a t RT had DM mode except No. 5 6 , which had IG. The FATT f o r No. 56 was 2250F. The DM f r a c t u r es u r f a c e s a l l had a v e r y small P s e g r e g a t i o n .D e t a i l e d SEM e v a l u a t i o no ft h e s ef r a c t u r es u r f a c e s r e v e a l e dv e r y small areas o fi n t e r g r a n u l a rf r a c t u r e ,t h u sa c c o u n t i n gf o r t h eo b s e r v a t i o n . The second series of s i x specimens was broken a t about O F by O using a c o o l i n gs t a g e on t h e AES. Two of samples, the No. 27 and No. 3 7 , s t i l l had DM f r a c t u r e mode and t h er e m a i n d e rf a i l e d by IG. Consequently, complete five sets o fd a t a were o b t a i n e d . i n c e S No. 56 had a v e r y h i g h l e v e l o f A s ( 2 4 3 ppm), a secondrun was c a r r i e d o u t * P h y s i c a lE l e c t r o n i c s AES No. 545 modified. tCambridgeStereoscan 1 5 0 , MK2 (1978).COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - " " A P I PUBL*757 8 2 m 0732270 0 0 8 7 5 2 8 7 m o nt h i ss a m p l es p e c i f i c a l l yt oe v a l u a t et h ep o s s i b i l i t yo f A s on t h e grain boundary. It was c o n c l u d e dt h a t As was n o tp r e s e n t , a t least w i t h i nt h er e s o l u t i o no ft h e AES used,whichfor A s i s approximately1.0 wt %. The g r a i nb o u n d a r yc o n c e n t r a t i o n sf o r Mo, C r , Fe, C, Cu and P f o re a c ho ft h ef i v es a m p l e s are shown i nF i g s . 51 t o 55. The maximum l e v e l s oftheelements a t o ra d j a c e n tt ot h eg r a i nb o u n d a r y are g i v e n i n Table 22. P r o f i l e s o ft h eg r a i nb o u n d a r yc o n c e n t r a t i o n s of N i and Sn were n o t drawnbecausemostofthedata were onthe limit o f r e s o l u t i o n i nt h ee x p e r i m e n t . The elements S, O and N c o u l db ed e t e c t e db u tt h e y r e v e a l e d no p a r t i c u l a rt r e n d .S u l f u ra n d - oxygen are normally found on a f r a c t u r es u r f a c ea f t e ri o ns p u t t e r i n g ,n o tn e c e s s a r i l y as anelementin t h e steel b u tr a t h e r as a s u r f a c ee n v i r o n m e n t a lc o n t a m i n a n t .S i m i l a r l y , t h el e v e lo fc a r b o no f t e ni n c r e a s e sd u et or e a d s o r p t i o n . Manganese and s i l i c o n were belowthe l i m i t o f r e s o l u t i o n o f t h e AES. The f r a c t u r e s u r f a c e s ofthebroken Auger specimens were i n s p e c t e d on a SEM and a l l found t o c o n t a i n i n t e r g r a n u l a r f a c e t s . Intermetationofthe Data F i g u r e s 51through 55 show t h e p r i m a r y c o n c e n t r a t i o n p r o f i l e s o f elements found on t h eg r a i nb o u n d a r i e s .I ne a c ho ft h ef i v es a m p l e sf o r w h i c h d a t a was o b t a i n e d , t h e r e was a v e r y d i s t i n c t p e a k o f P in the range of 3 t o 4 w t %. I ne a c hi n s t a n c e ,t h ep h o s p h o r u sl e v e lf e l lv e r y r a p i d l y f r o mt h eg r a i nb o u n d a r yt o 25 angstromfromthesurface.This i n d i c a t e st h a tt h ep h o s p h o r u ss e g r e g a t e st o form a v e r y t h i n f i l m on t h e grainboundaries.Phosphorus i s well known t ob et h ep r i m a r ye m b r i t t l - ingelementintemperembrittlement of Cr-Mo steels. The l i m i t o f r e s o l u t i o n o f C i s approximately 1 w t % andany u r e a d i n gb e l o wt h i s level shouldberegarded as q u a s i - q u a l i t a t i v e . Specimen No. 56 shows a v e r y clear Cu peak (2 w t X) whichdropstolow ( q u a l i t a t i v e )v a l u e sw i t h i n 2008 from t h es u r f a c e .S i n c et h ep r e s e n c e of Cu on t h eg r a i nb o u n d a r yi nt h i ss p e c i m e n i s u n a m b i g u o u s ,t h ep r o f i l e was drawn i nF i g . 54. The response from Cu can seen Fig. be in 56. For t h i sr e a s o nt h ep r o f i l eo b t a i n e df o rt h er e m a i n i n gs p e c i m e n s were drawn, s i n c et h eq u a l i t a t i v ed a t aa p p e a r e dt oc o n f o r mw i t ht h ed a t a from No. 56. Sample No. 63 shows no s e g r e g a t i o n f h e ot Cu. T h i s i s q u i t e con- s i s t e n tw i t ht h e l e v e l of Cu i n t h i s sample(0.02 w t W ) being somewhat lowerthanthe rest ( 0 . 1t o0 . 2 1 w t %). There i s no clear c o r r e l a t i o n betweenthe amount of Cu s e g r e g a t i o n and t h e w t % of Cu i n t h e s t e e l ( T a b l e s 21and22). The l e v e l s o f C, C r and M a t t h e g r a i n b o u n d a r i e s o r a d j a c e n t o t ot h eb o u n d a r i e s are a l l h i g h compared w i t ht h eb u l kc o m p o s i t i o n . Undoubtedly,carbidesonthegrainboundary may a c c o u n t f o r t h e h i g h C level up t o 16008 from t h es u r f a c e .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ . A P I PUBL*957 A 2 m 0732290 087529 0 O m . S e g r e g a t i o no f N i i s clear i n Sample No. 56 whichhasthe h i g h e s t N i c o n t e n t of t h e set (.23 w X ) . t The g r a i nb o u n d a r yc o n c e n t r a - t i o n of N i i Samples n 20, 26 and 43 i s q u a s i - q u a l i t a t i v e and t h el a c ko f N i on t h e GR i n Sample 63 i s c o n s i s t e n tw i t ht h e low N i level (.O6 w t W). S i m i l a r l y ,t h es e g r e g a t i o no f Sn i n Sample 56 i s clear, w h e r e a st h ed a t a f o r Samples 26 and 43 is q u a s i - q u a l i t a t i v e . DiscussionofResults The s e g r e a t i o no f P t ot h eg r a i nb o u n d a r i e s i s normally a s s o c i a t e d with temper e m b r i t t l e m e n t . However, s e g r e g a t i o n of Cu i s n o t commonly found. A c o n c e n t r a t i o no f 1 w t % Cu o nt h eg r a i nb o u n d a r i e s is g r e a t e rt h a nt h es o l i ds o l u b i l i t y of Cu i n i r o n o r steels.- The maximum s o l u b i l i t y a t room t e m p e r a t u r e i s -0.35 w 2.1101 C o n s e q u e n t l y ,t h e t Cu i s p r o b a b l yp r e s e n t on t h e g r a i n b o u n d a r i e s i n t h e form of small Cu-rich p r e c i p i t a t e s . me r o l eo f C i ne m b r i t t l e m e n to fs t e e l s [ l l lh a sb e e no f u c o n s i d e r a b l ec o n c e r ni nn u c l e a rv e s s e l sw h e r ee m b r i t t l e m e n to ft h e steel a f t e r i r r a d i a t i o n damage h a s b e e n a s s o c i a t e d w i t h h i g h e r l e v e l s of Cu (-0.4 w t % Cu) as w e l l as P. It i s r e p o r t e dt h a t 4.2 w t % Cu i n 2.25Cr - 1Mo - 0.2Si - 0.1C weld s t e e l caused a s h i f t of 5350F i n t h e t r a n s i t i o nt e m p e r a t u r e( a f t e ri r r a d i a t i o n at 5500F). nterestingly, he I t Auger a n a l y s i so f s t e e l s e m b r i t t l e d t h i s way showed no C on t h ef r a c - u ture s u r f a c e s . The e m b r i t t l e m e n t was t h o u g h tt ob ed u et ot h e combina- t i o n of r a d i a t i o n and Cu s o l u t e - d e f e c t a g g r e g a t e h a r d e n i n g . More r e c e n t r e s e a r c h byTakaku e t a l . [I2] d e m o n s t r a t e d t h a t t h e a d d i t i o n of Cu t o F e - i n d u c e d i n t e r g r a n u l a r f r a c t u r e a f t e r i r r a d i a t i o n b u tt h e yc o u l dn o td e t e c t Cu on t h eg r a i nb o u n d a r i e su s i n ga ne l e c t r o n microprobe. Pope e t a1.[131 i na ni n v e s t i g a t i o n of an SA533-B s t e e l , found Cu on t h e i n t e r g r a n u l a r f r a c t u r e s u r f a c e a f t e r a stress r e l i e f t r e a t m e n t a t 11350F f o r 6 h r . They comment t h a t Cu i s n o tn o r m a l l y a s s o c i a t e dw i t he m b r i t t l e m e n ti n steels. The same r e p o r t [ 1 3 1n o t e dt h a ti nt h e AES work, A s was notfound on t h eg r a i nb o u n d a r i e se v e nt h o u g ht h e A s l e v e l was -650 ppm. They s u g g e s t e dt h a tt h eo t h e rs e g r e g a t i n ge l e m e n t s (P, Sn, Sb, S , N, e t c . ) may h a v eo c c u p i e dt h ea v a i l a b l es e g r e g a t i o n s i t e s and t h e r e f o r ep r e - eluded A. s The maximum l e v e l of A i n t h e set t e s t i n g i n t h e API s t u d y s was -250 ppm. The presenceof Sn on t h e g r a i n b o u n d a r i e s c o i n c i d e s w i t h t h e o b s e r v e ds e g r e g a t i o n of N I , which i s a l s o c o n s i s t e n t w i t h t h e l e v e l o f N i i n each sample. has Tin been regarded as a ne m b r i t t l i n ge l e m e n ti n Ni-Cr-Mo-V r o t o r s t e e l s , 1141 whereas Yu and McMahon[151 found t h a t Sn d i dn o t( a l o n e )e m b r i t t l et h e Cr-Mo steels used i nt h e i rs t u d y .S i g n i - f i c a n t l y ,t h e steels used i nt h e l a t t e r s t u d y had no N i . I n a study of Ni-Cr-Mo-V s t e e l , [ l 6 1 b a s e d upon a s t a t i s t i c a l d e s i g n , .it was f o u n dt h a t t h ee x p r e s s i o nf o rt h es h i f ti nt h et r a n s i t i o nt e m p e r a t u r ea f t e rt e m p e r e m b r i t t l e m e n ti n c l u d e ds i g n i f i c a n t terms i n N i x Sn and P x Sn.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*959 8 2 W 0 7 3 2 2 7 0 0087530 7 Consequently, i t may b e i m p l i e d t h a t e i t h e r h i g h P o r h i g h N i are n e c e s s a r yt o br-ingabout embrittlement by The Sn. d a t ag e n e r a t e di nt h e API s t u d y are c o n s i s t e n t w i t h t h e s i g n i f i c a n c e o f t h e N i x Sn i n t e r a c - t i o n ,b u tt h e r e are too many v a r i a b l e s a v a i l a b l e t o c l e a r l y d e m o n s t r a t e t h i sp o i n t . The highcarbon l e v e l a d j a c e n t t o t h e g r a i n b o u n d a r i e s is a s s o c i a t e dw i t h GB c a r b i d e s . The h i g hl e v e lo f M may b ea s s o c i a t e d o withtheformationofMo-richcarbides[171 a t thetemperembrittlement t e m p e r a t u r eo rd u et o M s e g r e g a t i o n .S i m i l a r l y ,t h e o C a t t h eg r a i n r b o u n d a r i e sc a nb ea s s o c i a t e dw i t hc a r b i d e so rw i t ht h er e s u l t of s e g r e g a t i o n .W i t h o u t a c a r e f u la n a l y s i s of t h ec a r b i d e s ,t h ee f f e c t s cannotbereadilyseparated.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*957 82 m 0732270 0087531 7 W XI. FRACTURE TOUGHNESS EVALUATION (JIG) OF MMBRITLED AND ISOTHERMALLY EMBRITTLED SAMPLE NO. 75 Introduction as p a r t o ft h e API program on temperembrittlement, a comparison betweentheuppershelftoughnessbehaviorofunembrittled and temper embrittled 2 1/4 C r - 1Mo s t e e l i s being made. Whereas t h e o r i g i n a l i n t e n t i o n was t o u s e a steel h i g h l ys u s c e p t i b l et ot e m p e re m b r i t t l e m e n t , in f a c t no s a m p l e w i t h t h i s c h a r a c t e r i s t i c was l a r g e enough t o make twelve compact tension specimens. Amongst t h el a r g ep l a t e and forged s t e e l s a m p l e sa v a i l a b l e , No. 75 was s e l e c t e d . It had a s h i f t i n t r a n s i - t i o n AFATT of (550F) and AT ( 4 0 ) of (800F) a f t e rs t e p - c o o l e de m b r i t t l e - ment. (Table 3). From t h i sp l a t es a m p l et w e l v eb l a n k sf o r 2T compact t e n s i o n specimens were c u t .S i xo ft h eb l a n k s were t e s t e di nt h e" a s - r e c e i v e d c o n d i t i o n and t h er e m a i n i n gs i xp l a c e di n a f u r n a c e a t 8750F ( 4 6 8 % ) for 20,000-hr. isothermal embrittlement. ExDerimentalBackground The t e n s i l ep r o p e r t i e s ,h a r d n e s s ,c h e m i s t r y andstep-cooled t e m p e re m b r i t t l e m e n tp r o p e r t i e s , etc. f o r Sample No. 75, are l i s t e d i n T a b l e s 1, 2 and Table 3 . S i n c et h i ss a m p l e had a low y i e l ds t r e n g t h (-60 k s i ) , t h e l a r g e s t p o s s i b l e compact t e n s i o ns p e c i m e n s (2T) were made f r o mt h ea v a i l a b l e material i n o r d e r t o g i v e t h e g r e a t e s t p r o b a b i l i t y of o b t a i n i n gv a l i dd a t a .A l s od u et ot h ee x t r e m ed u c t i l i t yo ft h i s mate- r i a l i t Was n e c e s s a r y t o u s e JI^ a t e s t i n gp r o c e d u r ei no r d e rt o determine toughness. the The recommended methods for JI^ t e s t i n g were r e l e a s e dr e c e n t l y ,c o n s e q u e n t l yt h i s was anopportune time t o test t h e material accordingtotheprocedureswhich are o u t l i n e di nt h ep r o p o s e d s t a n d a r d . 1181 A s i n g l es p e c i m e n JI^procedureusingtheunloadingcompliance technique was used t od e t e r m i n et h e JI^ v a l u e a t a 5O0F t o 30O0F i n 5O0F i n t e r v a l s . The specimens were heated with heatertapes the and tempera- t u r ec o n t r o l l e dt ow i t h i n k4OF. The l o a d and d i s p l a c e m e n td a t a was f e d i n t o a Westinghouse 2500computer v i a a 1 2 - b i td a t aa c q u i s i t i o ns y s t e m . The v a l u e so fb o t h J and c r a c k e x t e n s i o n , a , were c a l c u l a t e d by a d a t a r e d u c t i o n program desc-ribed i n a paper Clarke Brown.[lg] by and The i n i t i a l t e s t a t lOOoF was t a k e nt o an a r b i t r a r yd i s p l a c e m e n tv a l u eo f 5.10 mm i n t h e hope t h a t s u f f i c i e n t c r a c k e x t e n s i o n wouldoccur.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 82 W 0732290 0087532 O m However, only crack extension values defined as crack tip blunting occurred at this displacement. The remainder of the tests were loaded in order to develop displacements up to 12.7mm.The test results are shown in Table 23. The values of J and for the various temperatures Aa tested can be seen in Figure 57. Discussion From Figure 57 it can be seen that at 500F and 1500F the value . of JlC is at some value greater than 1500 2 This high value of JI^ kJ/m results in apparent crack extensions due to crack tip blunting of at least 15 mm prior to the intersection of the R-line and the blunting line. The recommended JIc procedure was designed to test materials with less blunting than developed at these two temperatures. The values of JI^for the tests at 350°F, 250°F and 200°F are 700, 927 and 1050 kJ/m2, respectively. While the test data atl O O O F is not sufficient to deter- mine the value of JI it is reasonable to assume the value is also greater than 1500 kJTA2. Since the JI^ values are in doubt below 200°F, a plot of the load displacement curves normalized to the remaining ligament was generated (Figure 5 ) 8. The curves generated for the same steel after an isothermal embrittlement treatment of 20,000 hr. at 985OF were identical to those of the unembrittled condition. This probably reflects the fact that the transition temperature is comparable with or below 50°F, the lowest temperature used in JIc evaluations. An approximate estimate of a value KI^ may be obtained from of the expression v where F is Youngs modulus and is Poissons ratio. Conclusions of The high ductility and toughness this material resulted in extreme crack tip blunting prior to stable crack growth. The toughness of the material at temperatures below 2OO0F could not be determined using the procedure as outlined by the ASTM recommended practice JI^ for determination. After 20,000-hr. isothermal embrittlement at 875OF, the toughness was the same as measured prior to embrittlement.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 087533 0 2 m X I I . A STUDY OF THE EFFECT OF HIGH PRESSURE HYDROGEN ON THE: TEMPER EMRRITTLEMENT CHARACTERISTICS OF STEELS Cr-Mo Background I n 1979 a small “add-on” program was i n c o r p o r a t e d i n t o t h e API Temper Embrittlement study. The program was d e s i g n e dt oe s t a b l i s ht h e e f f e c to fh i g hp r e s s u r eh y d r o g e n a t temperembrittlementtemperatures (650 8750F) and on t h e known t e m p e re m b r i t t l e m e n tc h a r a c t e r i s t i c s of s t e e l s e m b r i t t l e d i n a i r . Some o ft h ed a t a were so u n u s u a lt h a tt h e API Committee on Temper E m b r 2 t t l e m e n tr e q u e s t e df u r t h e rr e s e a r c ht oc o n f i r m t h eo b s e r v e de f f e c t s . The a d d i t i o n a lt a s k s ,a n a l y t i c a lc h e m i s t r y , m e t a l l o g r a p h y ,c a r b i d em o r p h o l o g ye v a l u a t i o n s and f r a c t o g r a p h ys e r v e dt o c l a r i f y t o some e x t e n t t h e r e a s o n f o r t h e extreme embrittlementofone ofthesamples. ExperimentalBackground From t h ei n v e n t o r yo fr e m a i n i n gs a m p l e s ,t h r e e were s e l e c t e d f o r t h i s t u d yT h e s e . were sample nos. 46, 56 and 59. A t t h e 10,000 h r . i s o t h e r m a le m b r i t t l e m e n ts t a g ei n a i r , no. 46 showed no temper e m b r i t t l e m e n t , 56 t h e g r e a t e s t amount of e m b r i t t l e m e n t (a s h i f t i n t h e t r a n s i t i o nt e m p e r a t u r eo f 2000F) and59anintermediatedegreeof e m b r i t t l e m e n t of about 500F. S i x t e e n Charpyspecimens were machinedfromeach of t h e 3 s e l e c t e d steel samples. Eight specimens from each sample were p l a c e di n a na u t o c l a v e a t 6500F and t h er e m a i n d e ri na na u t o c l a v e a t 8750F. The h y d r o g e np r e s s u r ei nt h ea u t o c l a v e s was maintained a t 3,509psig.After 1,000 hr.exposurethespecimens were t a k e n . o u t a n d t e s t e d i n a Charpy impact machine. The d a t ag e n e r a t e d was t h e n compared with similar d a t a fromPhase II of t h e program f o r s p e c i m e n s e m b r i t t l e d i n a i r f o r 1,000 h r .( S e c t i o n IV). E x p e r i m e n t a l R e s ~ u l t s and D i s c u s s i o n (a) I n i t i a l Experiments TheCharpyimpactcurvedatafromthehydrogen-environment tests i s g i v e ni nT a b l e 2 4 , a l o n gw i t hd a t ap r e v i o u s l yo b t a i n e df o rs p e c i m e n s i s o t h e r m a l l ye m b r i t t l e d Ln a i r . The d a t ar e c o r d e di nT a b l e 24 g i v e sa nCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • estimate o f t h e u p p e r s h e l f v a l u e o r , a l t e r n a t i v e l y , i f t h e u p p e r s h e l f i s n o to b t a i n e d ,t h eg r e a t e s ti m p a c te n e r g yo b s e r v e d( i n d i c a t e d by >) . Basedupon t h e s ec o n s i d e r a t i o n st h ed a t a , i sa n a l y z e d as f o l l o w s . . No. 46 ( F e r r i t e - P e a r l i t e t r u c t u r e )T h i s a m p l e x h i b i t s S . l i t t l e o r no temperembrittlementin a i r o v e rt h er a n g e 650 t o 9 5 0 0 ~ . The6500Fhydrogen-environmentdataindicates a s l i g h td e g r e eo f e m b r i t t l e m e n t ,r e l a t i v et ot h e a i r d a t a ,b u tt h es h i f ti nt h e 40 f t - c l b TT i s b a r e l ys i g n i f i c a n t . The 8750F hydrogen-environment exposure r e s u l t e di n a r a d i c a lc h a n g ei np r o p e r t i e s . The FATT i n c r e a s e d by 500F a n dt h eu p p e rs h e l f was reduced from 240 f t - l bt o 25 f t - l b . Comparison o ft h e 40 f t - l b TT was t h e r e f o r en o tp o s s i b l e (see F i g u r e5 9 ) . No. 56 ( B a i n i t i cS t r u c t u r e ) .T h i ss a m p l eh a st h eg r e a t e s ts h i f t in FATT (AFATT) of t h e series s e l e c t e df o rP h a s e II oftheprogram. A f t e r 1,000 h ri s o t h e r m a le x p o s u r ei n air t h e s h i f t i n t h e t r a n s i t i o n temperatures was approximately 1000F. A f t e r 1,000 h r .i nt h eh y d r o g e n - environment a t 6500F a s i g n i f i c a n t i n c r e a s e i n t h e t r a n s i t i o n tempera- t u r e was foundwhereas,paradoxically, a t 8750F t h e s h i f t i n FATT was r e l a t i v e l y less t h a n t h a t r e s u l t i n g fromexposurein a i r (see F i g u r e 60). No. 59 ( B a i n i t i cS t r u c t u r e ) . The 1,000 h r . x p o s u r e o h e e t t hydrogen-environmentand air a t b o t h 650 8750F and resultedin e s s e n t i a l l y t h e same d e g r e eo fe m b r i t t l e m e n t (see F i g u r e6 1 ) . Fb )r t h e rs e a r c h ( u Re . S i n c et h er e s u l t so ft h eh y d r o g e n - e n v i r o n m e n te m b r i t t l e m e n t tests were so i n c o n s i s t e n t ,e s p e c i a l l yf o rs a m p l e4 6 , a few a d d i t i o n a l t a s k s were u n d e r t a k e ni na na t t e m p tt oc o n f i r mt h ed a t a .T h e s et a s k s wer e : ( i ) Compare a n a l y t i c a lc h e m i s t r yo fs a m p l e st a k e n from no. 46; (ii) Compare hardness specimens; of (iii) Compare m e t a l l o g r a p h i cs e c t i o n s of specimens sample from no. 46; (iv) Compare c a r b i d ee x t r a c t i o nr e p l i c a s fromspecimens of sample no. 46; (v) Examine f r a c t u r es u r f a c e of sample no. 46 a f t e r environmentalexposure.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 82 W 0 7 3 2 2 7 0 0 8 7 5 3 5 0 b m (i) AnalyticalChemistryofSpecimens fromSample No. 46 The a n a l y t i c a lc h e m i s t r yo ft h r e es p e c i m e n s from no. 46 was v e r y k i n d l yp r o v i d e d by M. R. L. Brooks Phoenix r of Steel. chemical The a n a l y s i s was p e r f o r m e db ys t a n d a r ds p e c t o g r a p h i ca n a l y s i sw i t h o u ta n y special rocedures. p The t h r e e p e c i m e n s were from s Charpy specimens whichhadbeenexposed to 8750F f o r 1,000 h r . i n a i r (46/A47) 650OF f o r 1,000 h r . i n H2 (46/EN8) 8750F f o r 1,000 h r . i n H2 (46/EN16) T h e s ec h e m i s t r i e s are compared w i t hd a t af r o m - a n" a s - r e c e i v e d "o r unexposed specimen obtained earlier i nt h e program i nT a b l e 25. The agreement i s very good and t h e r e f o r et h ep o s s i b i l i t yo fs p e c i m e n identification error is unlikely. ( i i ) HardnessReadings Rockwell B hardnessmeasurements were t a k e n fromspecimenswhich had beenexposedtothehydrogen-environment a t 650 8750F and f o r 1,000 h r . and compared withmeasurementsfromspecimens i nt h e" a s - r e c e i v e d " orunexposedcondition and specimens exposed i n a i r a t 8750F f o r 1,000 h r . The d a t a i s p r e s e n t e di nT a b l e 26. N o r m a l l y h e r e i s a degree t of s c a t t e r ( 5 t o 2 points)inhardnessmeasurementseventhoughthehard- nessmeasurementmachine is c a l i b r a t e dw i t hs t a n d a r d s whenever i t i s used. A a t r e n d ,b a s e d s upon the hardness measurements, i t a p p e a r st h a t t h e r e i s a s l i g h th a r d e n i n ga f t e rt h e 875OP a i r exposureandthe6500F 112 exposure and a s o f t e n i n g f h e ot steels a f t e r h e 7 5 O ~ x p o s u r e . t 8 e The s o f t e n i n g i s p a r t i c u l a r l y s i g n i f i c a n t i n t h e s a m p l e no. 46. (iii) Metallography of Sample No. 46 M e t a l l o g r a p h i cs e c t i o n so fs p e c i m e n si nt h e" a s - r e c e i v e d c o n d i - t i o n ,e x p o s e dt o a i r f o r 1,000 hr. a t 8 7 5 0 ~and exposedto 112 a t 650 and 875OF, were prepared. Apart from the H2-8750F specimen, metallo- the graphs are e s s e n t i a l l y similar i n p p e a r a n c e . a The s t r u c t u r e i s f e r r i t e - p e a r l i t e and t h eg r a i ns i z e s are comparable. The H2-8750F specimen has t h e same g r a i n s i z e as t h eo t h e rs p e c i m e n s ,b u tt h ef e r r i t e - p e a r l i t e Structurehasapparentlybeenreplaced by f e r r i t e g r a i n s w i t h l a r g e c a r b i d e s on t h eg r a i nb o u n d a r i e s .S i n c ef e r r i t e i s n o r m a l l ys o f t e rt h a n f e r r i t e - p e a r l i t e ,t h ec h a n g ei nh a r d n e s sw i t ht h es t r u c t u r ec h a n g e is c o n s i s t e n t .C o m p a r i s o n of t h em e t a l l o g r a p h s may he made from F i g u r e s 62 and 63. ( i v )C a r b i d eE x t r a c t i o nR e p l i c a s from Sample No. 46 In o r d e r t o o b t a i n a b e t t e rd o c u m e n t a t i o no ft h ec h a n g e si nt h e s t r u c t u r e of sample no. 46 a f t e re x p o s u r et ot h eh i g hp r e s s u r ee n v i r o n - m e n t - a t 8750F, c a r b i d e e x t r a c t i o n r e p l i c a s were prepared from t h e t h r e e 33COPYRIGHT American Petroleum Institute f .Licensed by Information Handling Services
  • . A P I PUBL*757 82 M 0732290 0 0 8 7 5 3 b 8 m specimens”A, B and C for which the analytical chemistry was carried out, viz. A. 875OF for 1,000 hr .. in air (46/A47) B. 650°F for 1,000 hr. in Hg (46/EN8) C. 8 5 F for 1,000 hr. in B2 (46/EN16) 7’ Transmission Electron Microscope (TEM) examination of the replicas was carried out and a number of high magnification micrographs taken. A few of these are reproducedin this report for comparison. Figure 64 shows a relatively low magnification micrograph of ofeach the A three specimens. The distribution of carbides in and B are distinctly different to those inC. Enlargements of the structures, including the grain boundaries, are shown in Figure 65. Figure 65.shows the presence of acicular carbides, which were found to a lesser extent in the other two specimens, A comparison of acicular carbides at a higher magnifi- cation is shown in Figure 66. It is clear that these carbides have grown significantly in the 875OF hydrogen environment. (v) FractoEraDhic Examination of Samples After Environmental Typical areas from the Scanning Electron Microscope (SEM) examinatjon of the fracture surface of a Charpy specimen from sample no. 46 after 1,000 hr. at 875OF 3,500 psig H2 are shownin Figure 67. in The lower magnification overview (Xl500) shows a mixture of cleavage and intergranular fracture. The intergranular faces, seen in detail in the higher magnification (XSOOO), exhibit polyhedral voids. These voids are not typical of dimpled rupture since they do not have the symmetrical cup-cone configuration normally associated with this mode of failure. After the same exposure sample no. 56 had a typical inter- granular and cleavage fracture surface (Figure8 . The higher magnifi- 6) cation picture of the intergranular face does not show any sign of void formation (or dimpled rupture). It is possible that micro-voids beyond the resolution of the SEM employed may exist. However, void formation 46 of the size and type found in sample was not present. (c) Discussion and Conclusions At first sight the results of the study appear to be contradic- tory since the steel that showed the least embrittlement in isothermal embrittlement in air (no.. 46) had the most radical change in properties after exposure to high pressure hydrogen in an autoclave at 875OF. The of metallography and the carbide extraction replica studyspecimens from no. 46 revealed, however, that the carbides had changed radically after the 875°F/1,000 hr. hydrogen exposure. This is consistent with the change in R hardness (Table 2 )6. The pearlite structure had dissolved B and large usters of carbides were formed on the grain boundaries. c This observation coupled with the void formation on the grain boundaries 34 H-.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBLx757 82 W 0732270 0087537 T W leads to the possible conclusion that the extreme changes in Charpy impact properties may be due primarily to grain boundary weakening (carbides and/or voids) caused by the effect of hydrogen. This cannot be explained within the limited work performed for this project.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ API -PUBL*757 82 W 0732270 087538 0 1 m XIII. ISOTHEEMAL EMBRITTLEMENT OF 1-1/2Cr-l/2Mo AND 3Cr-1Mo SAMPLES AT 875OF Three additional samples were assessed for isothermal embrittlement at 875OF. These were Sample NO Pe TY late lCr-l/2Mo 52 (1 PLA)R) (3 61 Forging 3Cr-1Mo 66 3Cr-1Mo Metal Shielded (3 Arc Weld SU) II The only other specimens tested in Phasein the 1Cr or 3Cr category were 4, 1Cr - 1/2Mo Submerged Arc Weld SAW) (1 and 65, 3Cr - lMo Submerged Arc Weld (3 SAW) for which the embrittlement data is reproduced above in Section IV. The isothermal embrittlement datas given in Table 27. A com- i parison of the step-cooied embrittlement data AT(40)u-E and the embrittle- ment due to isothermal embrittlement AT(40)(1000-~) ~T(40)(~0,000-~) and A(0(0 T4)2 O O O - ~ > is given in Table 28 along with the predicted data for isothermal embrlttlement based upon Eqs. (5) given in Section VII. The predicted isothermal embrittlements are reasonably good for the 3Cr-lMo samples, 61 and but poor for the 1,000 and 10,000 hr 66, condition of the 1-1/4Cr-1/2Mos sample 52. Here the term "reasonably good" means within the standard deviation of 35OF for the predictive equations developed in Section VII. COPYRIGHT American Petroleum Institute Licensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 0087537 3 m XIV. ACKNOWLEDGMENTS I is my sincere desire to acknowledge the patient and kindly t help in this large program all members of the I Task Group on of A P Temper Embrittlement: R. L. Brooks A R . . Ciuffreda E. H. Edwards (Chairman) J J . . Heller G. B. Kohut C A. . Robertson J. W. Thomas I have also been aided considerably in the following areas: Specimen layout and organization: G. E. Parker, R. Burland Metallography: G E . . Parker, R Burland, G. A. Blann . Analytical Chemistry: L. E. Creasy (Lukens Steel) J. Penkrot (Westinghouse R&D Center) Charpy Testing: R B . . Hewlett, R. R. Hovan, G. A. Mullen, Jr. Tensile Properties: J. J. Dufalla Computer Tabulation: B. J. Taszarek The 64 samples were provided by the following sources: Amoc0 Ashland Chicago Bridge and Iron Exxon Gulf Japan Steel Works Lukens Steel Soca1 Sohio Sun Oil TexacoCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*359 8 2 m 0732270 087540 0 T XV. REFERENCES 1. E H Edwards, Private Communication(1981). . . 2. Y. Murakami, T Nomura and J. Watanabe, May (1980), MPC/ASTM . Symposium, Denver Colorado. Also published as Japan Steel Works Report No. Ac80-5-21. 3. J. Watanabe and Y. Murakami, "Preventionof Temper Embrittlement of of CrMo Steel Vessels by Use Low Si Forged Steels," to be published, API Spring Meeting, Chicago, May(1981). 4. R Bruscato, Welding Journal, 49, 148-S (1970). . 5. G. C. Gould, ASTM Publication STP407, p. 59 (1967). 6. J Watanabe, Private Communication to . E H. . Edwards, July 17 (1975). 7. A. S . Tetelman and A. J. McEvily, Jr., "Fracture of Structural Materials," Wiley and Sons, New York, 325 p. (1966). 8. - R. E. Lorentz, Jr., Welding Jnl., p . 4405(1962). 41, 9. A. Joshi and D. F. Stein, "Temper Embrittlement Low Alloy of Steels," ASTM STP499, 59 (1971). 10. "Copper in Cast Steel and Iron," Copper Development Association Publication No. 29, p. 37 (1937). 11. of L. E. Steele, "Neutron Irradiation Embrittlement Reactor Pressure Vessel Steels," Int. Atomic Energy Agency, Vienna, Report No. 163, p. 187 (1975). 12. H. Takaku, et al., Jnl. NUC. Matls. 80, 57 (1979). 13. D. P. Pope, et al., "Elimination of Impurity-Induced Embrittlement in Steel," EPRI, NP-1501, September(1980). 14. D. L. Newhouse, et al., ASTM STP 499, 3 (1971). 15. J. Yu and C. J. McMahon, Jr., Met. .Trans. 11A, 277 and 291 (1980). 16. B J. Shaw, "A Temper Embrittlement Free Low Alloy Steel," . U.S. Patent 3,954,454 (1976).COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBLa757 8 2 W 0 7 3 2 2 7 0 0 8 7 5 4 3 0 3 W 17. C. J. McMahon, Jr., Third International Conference on the Effect of Hydrogen Behavior of Materials, Jackson Lake(1980). 18. G A,. Clarke, W. R Andrews, J A. Begley, J K Donald, G. T . . . . . . . Embley, J. D Landes, D E McCabe and J H Underwood, "A . . . . . Procedure for the Determination of Ductile Fracture Toughness Values Using J Integral Techniques," Jnl. Testing and Eval., JTEVA, Vol. 7, No. 1, January (1979), pp. 49-56. 19. G. A. Clarke and G. M. Brown, "Computerized Methods for JIc Determination Using Unloading Compliance Techniques," presented at of ASTM Symposium on Computer Automation Material Testing, Philadelphia, PA, November (1978), to be published.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - API PUBL*757 8 2 m 0732270 008751-12 3 m Table 1 Grain Size, Tensile Test Dataand Rockwell S Hardness Measurements of Samples Evaluated in Phase I 1 I I G r a i nS i z e Sample Number Kêy AS111 Number structurea Percent -~ " " _ "___ - "" _" " "" - ._ " - ___ . _____ - _ "____ 1 2 PLA 5.0 B 81.8 99.3 20.9 66.4 95.0 2 1 P U 8.0 F 45.5 76.4 32.1 68.8 79.0 4 1 SAIì 8.0 B 69.9 86.5 14.9 56.5 91.0 7 2 PLA 8.0 F 46.4 80.9 29.8 74.0 78. O 8 2 ESW 6.5 F 43.3 76.8 27.9 72.9 78.0 9 2 PLA 5.5 F 65.2 83.4 28.8 59.8 83.0 10 2 FOR 3.5 B 71.8 87.2 23.2 69.2 84.0 12 2 PLA 7.0 B 65.8 83.7 27.7 77.6 88. O 13 2 PLA 6.0 B 69.3 86.9 25.9 73.5 89. o 14 2 P U 6.5 B 60.5 80.9 30.6 77.8 87.0 15 2 FOR 6.5 B 71.5 87.7 27.5 76.3 89.0 16 2 ESW 8.0 B 66.2 85.7 25.0 72.1 87.5 18 2 SW A 7.0 B 91. o 19 2 SAI? 4.0 B 83.0 20 2 SAI? 4.5 B 87.0 21 2 SW A 4.0 B 81.0 22 2 SW A 6.5 B 80. o 23 2 SAW 4.5 B 88.5 24 2 SW A 4.0 B 86. O 25 2 SAW 4.0 B 89.5 26 2 ESW 2.5 B 83. O 27 2 ESW 6.0 B 88. O 33 2 PLA 5.0 B 95.0 111.7 22.0 68. O 90, o 34 2 SWA 6; O B 90.5 105.3 18.6 63.5 95. O 35 2 SAN 5.0 B 92.7 107.5 19.1 66.9 96. O 36 2 PLA 5.0 B 85.5 100.6 23.1 73.0 94. O 37 2 SAN 3.5 B 62.3 82.4 26.7 67.5 89.0 38 2 SAN 4.0 B 59.6 79.4 24.1 71.0 86.5 39 2 SAW 9.0 B 55.1 83.5 25.4 71.9 .86.0 40 2 SAI? 7.5 B 68.2 77.6 24.5 72.1 88. O 41 2 SWA .5.0 B 64.1 81.5 26.3 74.6 87.0 42 2 SAN 6.5 B 63.5 81.4 23.6 72. O 85. O 43 2 SWA 6.0 B 62.9 81.0 26.0 74.2 84. O 44 2 SWA 3.0 B 60.7 78.5 23.6 71.4 89.0 45 2 PLA 6.5 F 44.9 76.2 32.7 79.0 79. O 46 2 PLA 7.0 F 49.1 79.3 30.4 79.0 81, o 47 2 P U 8.0 B 68.2 85.5 28.0 81.0 89. o 48 2 PLA 8.0 B 69.2 86.4 27.2 81. o 90. o 50 1p u 7.5 F 50.4 74.5 34.5 69.4 81. o 52 1 PLA .o F 50.9 77.1 33.8 69.9 82. o 54 2 PLA 8.0 B 71.8 91.4 28.9 75.4 89. O 55 2 PLA 7.0 B 73.5 82.1 30.3 78.1 84.0 56 2 FOR 5.5 B 65.0 87.7 27.1 75.0 85.5 57 2 FOR 4.5 B 67.4 86.8 27.5 79.1 85.0 58 2 FOR 5.0 B 63.3 82.9 29. O 79.2 83.5 59 2 FOR 6.0 B 61.5 82.1 28.1 80.8 86. O 60 1p u 7.5 B 66.7 85.9 28.5 75.5 83.5 61 3 FOR 5.5 B 64.3 85.4 27.3 78.1 87.5 62 2 SWA 5.5 B 77.6 92.6 33.7 70.8 90. o 63 2 SMA 5.0 B 77.1 91.9 24.4 73.7 88. O 64 3 p u 8.0 B 58.1 80.6 31.8 78.7 82. o 65 3 SWA 6.0 B 64.0- 82.1 27.3 71.6 87.0 66 3 SMA 7.0 B 63.6 87.2 28.4 69.1 83.5 67 2 SMA 6.5 B 63.0 80.4 57.4 70.2 87. O 68 2 SA M 5.0 B 68. O 83.6 54.4 72.1 88.5 69 2 Sm 4.5 B 63.1 80.3 54.6 73.3 88.5 70 2 PM 5.0 B 62.4 79.7 26.3 72.5 84.0 71 2 PLA 5.0 B 63.4 82.4 27.2 71. O 87.5 72 2 PWI 5.5 B 63.9 82.4 29.1 76.7 86.5 74 2 PM 4.0 B 60.4 78.8 30.2 79.1 83.5 75 2 PL4 5.0 B 60.4 83.8 31.2 74.5 87.0 76 2 PM 7.0 * B-F 53.0 77.2 56.5 74.6 81.0 77 1FRO 6.5 F 41.7 75.6 32.3 70.5 78.5 78 2 FOE 8.0 F 45.6 77.8 30.3 72.6 80.o - "" F - Ferrite-Pearlite 40COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732210 087543 0 5 m i Table 2 - A n a l y t i c a l C h e m i s t r i e s of S a m p l e s E v a l u a t e d i n P h a s e I r- in Weight Percent - - - T - - - - - in Parts per Million - 1 Sample C Cr MO Mn Si Ni Cu P S Sn Sb O N AS Key = - - - - "" " " - "_ ~ - - " " ~ " - - __ ~ - "_ __ 1 .150 2.15 1.02 .42 .25 .18 .19 84. 211. 146. 29. 70. 99. 118. 2 PLA 2 .134 1.29 .47 .52 .59 .14 .13 100. 208. 230. 30. 32. 90. 80. 1 PLA 4 .O46 1.17 .44 . 9 1 . 5 3 .12 -28 79. 139. 87. 16. 1187. 108. 63. 1 SAW 7 ,139 2.20 1.00 k45 .26 .15 .16 100 192. 140. 34 * 16. 102. 108. 2 PLA 8 .121 2.27 . 9 1 .47 . 1 7 .24 .12 73. 126. 86. 17. 158. 121. 88. 2 ESW 9 .120 1.98 1.00 .44 .40 .12 .ll 72. 104. 86. 13. 33. 129. 63. 2 PLA 10 .116 1.95 1 . 0 5 .39 .20 .O8 .O6 52. 129. 56. 13. 42. 109. 52. 2 FOR 12 .129 2.29 1. o9 - 5 3 .24 .16 .13 54. 160. 87. 17. 190. 139. 84. 2 PLA 13 .125 2.13 .98 .48 a22 e21 .ll 74. 148. 118. 17. 185. 125. 62. 2 PLA 14 .133 2.25 .98 .45 . 2 1 . 1 7 ,o9 69. 154. 93, 12. 133. 108. 52. 2 PLA 15 .123 1.99 .92 .44 .35 .10 .O8 120, 93. 57. 16. 28. 118. 54. 2 FOR 16 .140 2.11 . 9 1 . 6 1 .21 .15 . o9 97. 130. 68. 38. 188. 129. 67. 2 ESW 18 .O75 1.94 .87 .81 . 5 1 .20 .13 48. 173. 135. 20. 758. 153. 118. 2 SAW 19 .O70 2.35 1.10 .39 .24 .16 .O5 124. 145. 58. 8. 266. 109. 66. 2 SAW 20 .121 1.97 .86 .52 .28 . 1 3 . 2 1 100. 121. 147. 20. 337. 123. 100. 2 SAW 21 .O55 2.20 1.05 .62 .42 .14 02 75. 188. 47. 6. 739. 167. 58. 2 SAW 22 .O78 2.22 .90 .64 .39 .12 .o2 79. 162. 62. 8. 760. 110, 50. 2. SAW 23 .O81 1.89 .94 .82 .48 .14 . 2 1 103. 145. 149, 19. 575. 126. 29. 2 SAW 24 .O47 2.14 .85 .70 .47 13 .O5 175. 184. 63. 6. 769. 147. 139. 2 SAW 25 .O95 1.92 .86 .81 .47 . 1 4 .21 98. 160. 162. 19. 482. 119. 78. 2 SAW 26 .146 2.25 . 9 3 . 6 1 .25 .15 .10 91. 127. 188. 25. 144. 127. 47. 2 ESW 27 .168 2.22 .92 .59 .21 . 1 3 .O8 64. 135. 75. 15. 93. 121, 92. 2 ESW 33 .119 1.96 .98 .38 .31 .21 .21 78. 195. 172. 29. 178. 119. 88. 2 PLA 34 .O78 2. o1 .85 .84 .45 .23 .29 85. 165. 102. 21. 602. 149. 91. 2 SAW 35 .O79 2.01 .91 .89 * 45 .23 .34 103. 95. 86. 21. 564. 182. 71. 2 SAW 36 .lo7 2.09 .93 .34 . 2 1 .29 .17 57 * 187. 109. 24. 53. 72. 78. 2 PLA 37 ,067 2.15 e77 .96 .54 .12 .o2 118. 110. 43. 11. 653. 125. 34 * 2 SAW 38 .O72 2.21 1.20 - 7 7 .44 .12 .o2 110 6 140. 39. 9. 932. 115. 31. 2 SAW 39 .O53 2.40 .95 - 7 3 .32 * 1 2 .15 174. 107. 76. 19. 376. 122 * 142. 2 SAW 40 .O66 2.35 .90 - 7 3 .28 .10 e12 139. 115. 78. 19. 452. 100. 150. 2 SAIJ 41 ,056 2.26 .87 .72 .37 .10 , 1 3 163. 93. 78. 19. 368. 125. 146. 2 SAW 42 ,055 2.40 . 9 1 .74 . 3 1 .12 .14 162. 100. 68. 19. 474. 125, 113. 2 SAW 43 ,058 2.41 .97 - 6 7 .32 .10 .16 190. 77. 69. 21. 412, 137. 200. 2 SAW 44 .O56 2.28 .81 .69 .38 . o7 .13 167. 95. 83. 20. 394 * 120. 213. 2 SAW 45 .lo8 2.25 .80 I44 .19 .17 .24 113. 32. 161. 30. 29. 90. 123. 2 PLA 46 .lo8 2.34 1.08 . 4 3 .17 .25 .19 103. 31. 149. 30. 28. 92. 119. 2 PLA 47 . 1 1 1 2.21 .84 . 4 3 .23 .16 .24 88. 30. 157. 30. 24. 86. 127. 2 PLA 48 ,110 2.30 .97 - 4 3 .19 .19 .25 1 11 . 30. 157, 30. 21. 86. 128. 2 PLA 50 ,141 1.20 .42 I 48 .60 . 1 3 .O8 212 131. 81. 21. 40. 131. 328. 1 PLA 52 ,143 1.29 44 - 5 4 . 6 3 .22 .11 168. 107. 140. 35 * 29. 136. 380. 1 PLA 54 ,125 ,126 2.19 2.23 9 * 93 I47 .47 . 1 3 . o9 143. 42. 106, 21. 51. 142. 249. 2 - PLA 55 .97 - 4 5 .39 .16 * 10 130. 52. 112. 20. 35. 145. 307. 2 PLA 56 ,148 2.22 1.20 - 5 8 .28 . 2 3 .17 164. 90. 203. 42. 36. 90. 243. 2 FOR 57 ,128 2.23 .86 v53 .24 .18 . o9 68. 36. 125. 23. 26. 83. 168. 2 FOR 58 B143 2.32 .94 , 5 6 .14 .18 .12 130. 48. 183. 31. 25. 76. 208. 2 FOR 59 I144 2.35 95 I 5 1 .O4 . 1 4 .O8 63. 55. 115. 24. 29. 96. 122. 2 FOR 60 150 1.32 .40 52 .66 , 1 5 * 10 125. 17. 149. 35. 26. 73. 253. 1 PLA . I I 61 I152 2.92 .87 I57 o9 .17 .14 100. 60. 155. 30. 29. 110. 177. 3 FOR 62 ,062 2.44 1 . 1 7 I44 .37 .10 . O 8 146. 45. 69. 16. 384, 174. 82. 2 SAW 63 ,068 2.26 .82 I 60 .35 .O6 .o2 126. 40. 81. 52. 318. 215. 115. 2 SMA 64 ,141 2.90 .96 v53 .O6 .10 .O6 107. 68. 3 PLA 65 66 I057 105 3.16 1.13 , 8 0 .35 2.82 1.02 , 5 2 .40 .O7 . . o9 o9 152. .o2 98. 71. 62. 63. 94 * 20. 52. 29. 30. 93. 379. 291. 485, 199. 29. 45. 3 SAW 3 SMA I 63. 63. 67 ,047 2.20 ,99 I 7 1 .35 .O4 S 02 116. 240. 46. 8. 543 * 107. 50. 2 SMA 68 ,067 2.18 L. 08 ,65 .36 .O4 .o2 52. 160, 48. 4. 466. 81. 39. 2 SMA 69 ,100 2.13 .95 $ 5 3 .26 .O4 .o2 96. 172. 50. 5. 491. 143. 48. 2 SMA 70 ,110 2.11 .95 t 39 .24 .15 .12 58. 98. 98. 24. 57, 73. 68. 2 PLA 71 ,131 2.25 .97 , 4 3 .25 .14 .19 92. 196. 213. 40. 65. 84. LOO. 2 PLA 72 ,123 2.22 .90 I47 .30 .10 .13 70. 180. 120. 20. 67. 68. 67. 2 PLA 74 ,103 2.28 l. O0 , 4 1 . 2 1 .15 .15 73. 162. 151. 33. 59. 74. 103. 2 PLA 75 I139 2.19 .86 , M .47 .14 . o9 175. 50. 124. 28. 30. 140. 387. 2 PLA 76 ,118 2.26 .78 I46 .18 .23 . 1 3 106.. 164. 116. 19. 112. 95. 84. 2 PLA 77 ,140 1.34 .45 , 5 1 .60 .18 .17 108. 173. 145. 22: 23. 78. 90. 1 FOR 78 126 2.16 .98 I45 ,26 .16 .14 83. 152. 257. 19. 98. 77. 2 FOR -- - - - - 29. I ~ - - - 41COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*759 8 2 m 0732270 0 0 8 7 5 q 4 7 m T a b l e 3. Data DerivedfromCharpyImpact Tests f o rS a m p l e s E v a l u a t e d i n Phase I. Data f o rs a m p l e si n d i c a t e d by a n a s t e r i s k was s u p p l i e d by material o r i g i n a t o r a n d was t e s t e d w i t h t h e Phase II o r i e n t a t i o n . See F i g .4 5 d 40 ft-lb TT Jpper h Upper i Sampli Numbex ~- 2L F A T T ~ FATT AFATT Ue Ef A T ( 4 O l g heit11 (Dea ees F m e n h e i t ) ;helf (f oot-po Shelf I s d ) 1 2 PLA 65. 80. 15. 30. 40. 10. 88. 88. 2 1 PLA 20. 60. 40. - 35. - 50. - 15. 155. 140. 4 1 SW A 100 100 O 190. 140. - 50. 49. . 48. 7 2 PLA 5. 30. 25. - 30. - 2 5 , 5 138. 140. 8 2 EW S 50 75. 25. 40. 50. 10 110. 108. 9 2 PLA - 25. 35. 60 i -150. - 20. 130. 160. 152. 10 2 FOR 10. - 10, - 20. -110. - 5. 105. 116. 112. 12 2 PLA -105 - 35. 70. -110. - 70. 40. 160 .. 160. 13 2 PLA - 80. - 15. 65. -145. - 40. 105. 120. 132. 14 2 PLA - 75. - 30. 45. -110. - 60. 50. 170. 156. 15 2 FOR - 80 35. 115. -130. - 50, 80. 166. 156. 16 2 EW S - 40. O. 40. - 65. - 50. 1 5 . 105. 100. 18* 2 SAW 90. 232. 142. 40. 192. 152. 90. 19" 2 SAW 54. 64. 10. 23. 42. 19. 114. 114. 20* 2 SW A 30. 44. 14. 6. 16. 10. 118. 114. 21* 2 SAW 60. 90. 30. 74. 94. 20. 100. 90. 22* 2 SW A 60. 90. 30. 74. 94. 20. 100. 90. 23* 2 SW A 42. 80. 38. O. 60. 60. 110. 100. 24" 2 SAW 72. 140. 68. 58. 120. 62. 96. 80. 25* 2 SAW 16. 92. 76. 6. 68. 62. 86. 78. 26* 2 EW S - 80. - 4. 76. - 92. - 32. 60. 96. 85. 27 * 2 EW S - 48. - 24. 24. - 56. - 40. 16. 140. 130. 33 2 PLA 5. - 15. - 20. - 50. - 40. 10. 120. 120. 34 2 SW A - 30. 35. 65. - 25. 40. 65. 70. 67. 35 2 SW A - 40. 80. 100. - 30. 35. 65. 80. 80. 36 2 PLA 20. -65. 55. - 50. 40. 90. 135. 122. 37 2 SW A 50. 190. 140. 10 135. 125. 110. 80. 38 2 SW A 75. 110. 35. 55. 90. 35. 100. 95. 39 2 SAW 20. 85. 65. - 45. 5. 50. 110. 116. 40 2 SAW - 10. 50. 60. - 50. - 25. 25. 135. 120, 41 2 SW A - 20. 125. 105. - 70. 55 125. 120. 120. 42 2 SW A - 20. 98. 118. - 70. - 10. 60. 110 112. 43 2 SAW - 50. 87. 137. - 80. 35. 115. 125. 124 44 2 SW A 10. 110 120 - 40. 17. 57. 125. 112. ContinuedCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services .. .
  • A P I PUBL*757 8 2 m 0732270 0087545 7 H T a b l e 3. (Continued) d 40ft-lb TT h Ipper Upperi Sample F A T T ~ F A T T ~AFATT Ue Ef AT(40)g Shelf Shelf Key Numb e r " (Degrec Fahr e h e i t ) (De rees F a h r e n h e i t ) " ( f o o t pounds) " - 33. - 70. - 8 0 . - 10. " 45 2 PLA - 50. 17. 220. 240. 46 2 PLA - 40. - 5. 35. - 75. - 65. 10. 230. 240. 47 2 PLA -130. - 70. 60. -195. -100. 95. 235. 230. 48 2 PLA -140 -130 1 0 -14 O -135 5. 235 210. 50 1 PLA 70. 85. 15. 30. - 25. - 55. 120. 145. 52 1 PLA 80. 95. 15. O. 40. 40. 120. 125. 54 2 PLA - 25 - 5. 20. -115. - 85. 30. 200, 180. 55 2 PLA 10 30. 20. - 70. - 40. 30. 180. 175. 5 69: 2 FOR O. 122. 122. - 44. 68. 112. 120 120. 57* 2 FOR - 87. - 78. 9. -110. - 90. 20. 210. 203. 58* 2 FOR - 64. - 24. 40. -104. - 88. 16. 203. 218. 59* 2 FOR - 73. - 66. 7 . -133. -119. 14. 160. 160. 60* 1 PLA 30. 52. 22. - 36. - 2. 34. 203. 181. 61* 3 FOR - 77. - 58. 1 9 . -101. - 92. 9. 189. 167. 622 2 SAW 43. 59. 16. 21. 34. 13. 131. 131. 63* 2 SMA - 8. 19. 27. - 27. 7. 34. 152. 131. 64 *3 PLA - 83. - 80. 3. - 96. - 96. o. . 167. 167. 659; 3 SAW 25. 63. 38. 3. 35. 32. 116. 109. 6 i:6 3 . SMA - 35. 30. 65. - 47. - 4. 43. 116. 116. 67 2 SMA 5. 60. 55. - 60. 15. 75. 120. 115. 68 2 SMA 30. 45. 15. 1 0 . - 25. - 35. 115. 110. 69 2 SMA - 5. 15. 20. - 50. - 30. 20. 140. 130: 70 2 PLA O. 50. 50. - 10 15. 25. 140. 145. 71 2 PLA - 10. 45. 55. - 1 5 . 20. 35. 100. 100. 72 2 PLA - 65. - 5. 60, - 80. - 90. - 1 0 . 145. 165. 74 2 PLA - 70. - 20 50. - 8 0 . - 55. 25. 165. 165. 75 2 PLA - 25. 30. 55 -120. - 40. a 80. 180. 160. 76 2 PLA 70. 85. 15. 50. 35. - 15. 115, 120. 77 1 FOR 65. 80. 15. 35. 20. - 1 5 . 150. 110. 78 2 FOR 50. 80. 30. 1 5 . - 25. - 40. 115. 115. aF r a c t u r e A p p e a r a n c e T r a n s i t i o n T e m p e r a t u r e i n theunembrlttledcondition bFractureAppearanceTransitionTemperaturein the s t e p - c o o l e d e m b r i t t l e d c o n d i t i o n C Change i n F r a c t u r e A p p e a r a n c e T r a n s i t i o n T e m p e r a t u r e d u e t o temper embrittlement d40 f o o t / p o u n d T r a n s i t i o n T e m p e r a t u r e e Unembrittled fStep-cooledembrittled gChange i n 40 f o o t / p o u n d T r a n s i t i o n T e m p e r a t u r e d u e t o t e m p e r e m b r i t t l e m e n t h U n e m b r i t t l e dc o n d i t i o n i Step-cooledembrittledcondition 43COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • m m I_ A P I PUBL*757 8 2 0732270 0087546 O TABLE 4 Comparison of FATT After Data Isothermal of 1000 hr in "F Embrittlement O Phase II orientation, Fig.45 Sample No.. Furnace Temperature I 650°F 75F 2 800F 875°F 950°F 1 75 75 90 110 110 4 145 125 150 175 130 9 -25 10 15 -30 35 16 -15 5 -30 O 30 19 55 70 70 60 85 20 30 25 25 35 40 26 60 50 65 70 135 27 -10 -15 25 45 30 33 30 O 10 20 5 36 60 30 45 60 20 37 70 90 50 90 80 43 20 10 50 50 75 44 20 35 55 80 90 46 - 30 -15 O -10 -10 47 -70 -85 -60 -50 -55 54 -25 -15 O 25 25 56 40 40 90 125 150 59 -15 -10 40 25 -5 62 45 55 80 75 90 63 20 25 70 35 75 65 60 90 100 90 70 67 25 15 45 50 75 68 40 30 50 60 50 69 45 30 50 50 30 78 60 80 . 75 85 60 44COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 82 W 0732270 0087547 2 W Table 5 Comparison of 40 ft-lb TT After Isothermal Embrittlement of 1000 hr in "F Phase II orientation, Fig.45 Sample No. r 650°F Furnace 725°F Temperature 800o F 875°F 950°F 1 40 25 65 85 85 4* 160 110 150 190 135 9 -85 -90 -65 -60 -40 16 -50 -15 -75 -45 -20 19 35 35 45 20 50 20 -15 -5 5 10 20 26 5 20 40 50 55 27 -35 -20 5 15 10 33 -10 -20 -10 -5 -15 36 45 -5 10 15 -20 37 40 65 40 40 25 43 - 85 -65 -65 -20 15 44 -70 -5 -10 O 10 46 -55 -50 -25 -45 -55 47 -100 -105 -115 -100 -95 54 -100 -85 -110 -100 -70 56 -30 -40 30 -10 60 59 -80 -125 -75 -75 -90 62 20 15 35 40 55 63 5 5 5 20 40 65 50 70 75 60 25 67 -40 -10 O -10 10 68 -10 O 35 - 20 25 69 15 -5 20 O O 78 20 . 20 25 20 25 Upper shelf close 40 ft-lb. to 45COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*759 8 2 W 0 7 3 2 2 9 0 008754A 4 H TABLE 6 Comparison of Estimates of the Upper Shelf Impact Energy After Isothermal Embrittlement 1000 hr in "F of (> means insufficient data accurately determine value: to figure given is the highest recorded) Phase II orientation, Fig.45 S amp No. le Furnace Temperature 1 650°F 725°F 800°F 875°F 950°F 1 80 70 80 80 85 4 50 53 50 50 50 9 175 160 175 150 150 16 >110 >90 >120 ND 115 19 90 115 10o 95 100 20 115 >110 110 115 >lo8 26 >120 110 105 120 90 27 110 105 >lo5 100 >loo 33 >85 85 85 90 10o 36 >120 120 >115 120 >128 37 115 110 - 90 ND 143 43 150 135 >110 120 >115 44 140 120 120 105 105 46 >190 240 >220 245 220 47 >217 >180 240 240 >180 54 >240 190 >190 170 >180 56 >160 140 >130 130 >115 59 >180 >195 >210 170 >170 62 >150 >110 >125 . >139 145 63 >120 >110 >145 140 140 65 >161 115 125 120 140 67 120 >115 >115 >120 >110 68 100 100 >loo >110 100 69 110 90 >110 105 120 78 105 105 105 110 >120 46COPYRIGHT American Petroleum Institute .Licensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 0087547 b m TABLE 7 Comparison of FATT Data After Isothermal Embrittlement of 10,000 hr in "F Phase II orientation, Fig. 45 1 Sample No. l- Furnace Temperature 650°F 725°F 800°F 875°F 950°F 1 90 80 115 110 100 4 120 120 115 97 115 9 -10 -60 5 110 85 16 O -10 10 40 20 19 55 60 75 75 60 20 25 40 55 45 10 26 60 40 80 140 135 27 O -5 60 55 35 33 10 15 30 10 25 36 50 25 25 10 15 37 55 50 140 50 110 43 30 30 85 120 75 44 30 15 105 110 130 46 -25 -15 - 30 -5 -20 47 . -75 -75 -25 -20 -20 54 -40 -25 10 30 50 . 56 45 75 180 240 175 59 -25 -10 10 O O 62 50 45 80 90 80 63 40 40 90 90 95 65 50 100 120 165 180 67 10 40 85 120 95 68 20 35 50 85 70 69 35 30 50 30 55 78 70 65 75 60 70COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • " A P I PUBL*757 8 2 3 2 2 9 0 8 7 5 5 0 07 00 2 m TABLE 8 Comparison of 40 ft-lb TT Data After Isothermal Embrittlement of 10,000 hr in F Phase II orientation, F i g . 45 Sample No. Furnace Temperature 1 1 60F 5 75F 2 80F 0 85F 7 90F 5 1 .- 25 40 90 95 65 4 125 175 110 110 115 9 -45 -75 -50 -20 O 16 - 35 - 20 -10 15 O 19 40 55 55 60 50 20 10 5 30 40 -5 26 35 10 45 75 60 27 - 30 -25 30 20 -5 33 -25 -10 O 5 -5 36 -5 20 .5 O -25 37 40 50 85 50 90 43 -95 -60 O 35 35 44 -45 -25 5 40 50 46 -50 -20 -50 -40 -50 47 -125 -110 -85 -100 -110 54 -95 -100 -75 -40 -60 56 -40 -10 80 150 75 59 -80 -90 -55 -50 -80 62 15 20 35 40 45 63 15 10 30 50 50 65 15 55 50 115 110 67 -25 -20 45 75 50 68 10 10 . 25 70 25 69 20 O 5 15 10 78 25 10 O 25 25COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm959 8 2 W 0732270 0087551 4 W TABLE 9 Comparison of Upper S h e l I m p a cE n e r g i e s f t e r f t A 1 0 , 0 0 0h rI s o t h e r m a lE m b r i t t l e m e n t( i nf t - l b ) Phase II o r i e n t a t i o n , F i g . 4 5 Sample No. T FurnaceTemperature 650°F 725°F 800°F 875°F 950F 1 ND >90 >95 >87 84 4 58 40 54 51 71 9 187 >170 >170 >185 239 16 150 >125 >lo6 > 85 125 19 >136 >lo5 >110 >115 107 20 136 ND >125 115 139 26 134 >125 >110 110 116 27 119 >110 >120 >120 126 33 >86 >80 >86 >lo5 85 36 140 >120 ND ND >123 37 >121 ND ND 240 >123 43 >240 >lo5 ND 240 162 44 >150 >125 >loo >115 >143 46 >240 >240 >140 240 239 47 >240 >225 >160 ND 239 54 240 >200 >190 24 O 239 56 160 >156 >loo 115 181 59 200 >194 >190 >195 208 62 155 ND ND >110 150 63 >240 >170 >136 ND >177 65 1 57 ND >115 >200 >192 67 132 >112 >112 >110 114 68 126 >115 >110 >115 110 69 >118 >125 ND >140 >145 78 >126 >125 ND ~125 119 ND = Not Determined. > = Greater t h a n o r h i g h e s t v a l u e r e c o r d e d .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 W 0 7 3 2 2 7 0 0 8 7 5 5 2 0 b W TABLE 10 Comparison of FATT Data A f t e r s o t h e r m a l I Embrittlementof20,000 h r i n "F Phase II o r i e n t a t i o n , F i g . 45. "----r Furnace Temperature Sample No. 650F 725°F 800°F 875 "F 950°F 1 95 90 125 110 100 4 130 130 135 85 75 9 5 O 25 85 90 16 25 5 20 50 25 19 50 50 75 70 65 20 40 45 65 75 50 26 55 55 120 145 170 27 -15 -10 30 50 20 33 -10- O 15 25 30 36 30 25 50 45 40 37 50 85 60 175 60 43 35 25 75 135 95 44 30 40 75 150 135 46 -25 -10 10 10 10 47 -75 -60 -20 O 15 54 -20 -15 35 70 75 56 50 100 200 225 175 59 -60 O 15 25 5 62 50 60 125 100 100 63 50 55 90 90 90 65 60 70 150 . 110 100 67 40 70 110 110 100 68 50 50 65 80 50 69 30 35 50 50 60 78 45 80 60 85 90COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - . A P I PUBL*759 82 m 0732290 0087553 B m TABLE 11 Comparison of 40 ft-lb TT Data After Isothermal Embrittlement of 20,000 hr in " F Phase II orientation, F i g . 45 Sample Furnace Temperature 1 No. 650°F 725°F 800°F 875°F 950°F 1 65 70 105 80 65 4 145 160 120 65 75 9 -35 -40 -25 35 5 16 -5 -10 10 20 O 19 40 35 75 70 35 20 10 25 45 . 50 - 30 26 15 45 70 95 100 27 -45 -60 30 40 O 33 - 20 -10 O 20 20 36 O -5 -10 O O 37 35 60 50 140 55 43 O -20 O 30 40 44 -40 -50 10 25 60 46 -50 -50 -30 -30 -25 47 -115 -100 -75 -75 -55 54 -75 -75 -50 O -10 56 -25 O 100 125 75 59 - 85 -75 -15 -15 -50 62 35 25 50 45 45 63 10 30 45 55 40 65 55 40 70 70 50 67 - 20 10 60 20 50 68 25 25 40 50 45 69 40 O 30 O 15 78 O 10 15 10 30COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • TABLE 12 Comparison of Upper Shelf Impact Energies After 20,000 hr Isothermal Embrittlement (in ft-lb) Phase II orientation, P i g . 45 Furnace Temperature Sample No. 950°F 60F 5 725°F 800OF 875 OF 1 90 90 85 90 90 4 50 50 60 65 75 9 205 160 160 180 155 16 105 115 115 100 110 19 100 110 110 15 0 >85 20 125 90 110 130 130 26 110 115 110 95 115 27 110 115 105 105 115 33 . 1o 0 100 85 90 95 36 130 140 130 110 >95 37 160 120 120 115 145 43 135 135 130 155 220 44 130 120 120 130 120 46 240 240 240 240 240 47 240 240 240 240 >180 54 220 200 180 230 160 56 160 160 145 135 150 59 190 230 225 240 230 62 150 160 165 130 150 63 175 180 160 165 150 65 15 5 >130 160 140 135 67 135 130 125 120 120 68 110 110 105 120 100 69 125 120 115 110 150 78 125 120 115 100 95COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBLa959 8 2 m 0 7 3 2 2 7 0 0 0 8 7 5 5 5 I m TABLE 13 Comparison of FATT i n De-Embrittled ( D ) , U n e m b r i t t l e d (U) a n dS t e p - C o o l e dE m b r i t t l e d ( E )C o n d i t i o n si n O F P h a s e I o r i e n t a t i o n ,F i g .4 5 Sample Type D U E No. 1 2 PLA 80 65 80 4 1 SAW 125 100 , 100 8 2 ESW 70 50 75 9 2 PLA -50 -25 35 16 2 EW S -10 -40 O 18 2 SW A 50 90* 2325; 19 2 SW A 30 54* 64* 20 2 SW A O 305; 44* 24 2 SW A 70 725~ 140* 26 2 ESW 40 -80* -45; 27 2 ESW -60 -482 -24* 33 2 PLA -35 5 -15 36 2 PLA 5 20 65 37 2 SW A 40 50 190 38 2 SW A 50 75 110 44 2 SAW O -10 110 46 2 PLA -55 -40 -5 47 2 PLA -90 -130 -70 52 1 PLA 50 80 95 54 2 PLA -60 -25 -5 56 2 FOR 25 0 5c 122* 61 3 FOR -45 -77* -58* 66 3 SMA -10 -35* 30* 67 2 Sm -15 5 60 68 2 SMA 25 30 45 69 2 SMA 20 -5 15 78 2 FOR 35 50 80 KEY 1, laCr - %Mo FOR, Forging 2, 2aCr &Mo- PLAY P l a t e 3, 3Cr - 1Mo SAW, Submerged arc weld ESW, E l e c t r o s l a g w e l d SMA, S h i e l d e d metal a r c weld *Data r e p o r t e d b y material o r i g i n a t o r . 53COPYRIGHT American Petroleum Institute ~-< .Licensed by Information Handling Services
  • A " " " - . A P I PUBL*757 8 2 m 0732270 087556 0 3 m TABLE 1 4 Comparison f 0 t-lb o4 f TT i n De-Embrittled (D), U n e m b r i t t l e d (U) andStep-CooledEmbrittled(E) C o n d i t i o n s i n F P h a s e I o r i e n t a t i o n , F i g . 45 Samp l e Type D .U E No. 1 2 PLA 50 30 40 4 1SWA 150 190 140 8 2 ESW 40 40 50 9 2PIA -70 -150 -20 16 2 ESW -25 -65 -50 18 2 SAW 35 40* 192* 19 2 SW A 30 23* 42* 20 2 SW A -50 6* 16* 24 2 SAW 50 5 8* 120* 26 2 EW S O -92* -32* 27 2 EW S - 70 -56* -40 33 2 PLA -40 -50 -40 36 2 PLA -10 -50 40 37 2 SAW 10 10 135 38 2 SW A 45 55 90 44 2 SW A -75 -40 17 46 2 PLA - 70 -75 -65 47 2 PLA -140 -195 -100 52 1 PLA -45 O 40 54 2 PLA -120 -115 -85 56 2 FOR -45 -44* 6 85: 61 3 FOR -105 -lOl* -92s: 66 3 SMA -60 -47* -4?: 67 2 SMA -50 -60 15 68 2 SMA -10 10 -25 69 2 SMA 5 -50 -30 78 2 FOR -15 15 -35 KEY 1, 1 % C r - %Mo FOR, F o r g i n g 2, 2kCr - %Mo PLAY P l a t e 3, 3Cr - 1Mo SAW, Submerged arc weld ESW, E l e c t r p s l a g w e l d SMA, S h i e l d e d metal a r c weld *Data reported by material o r i g i n a t o r . 54 .- .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 087557 0 5 m TABLE 15 Comparison of Upper S h e l f n e r g i e s E i n De-Embrittled (D), U n e m b r i t t l e d (U) andStep-CooledEmbrittled (E) Condi- tions in ft-lb Phase I orientation, ig. 5 F 4 Sample U E Type D No. 1 2 PLA 100 88 88 4 1 SW A 65 49 48 8 2 EW S 120 110 108 9 2 PLA 180 160 152 16 2 EW S 105 105 100 18 2 SW A >75 90* -* 19 2 SW A 140 114* 1145; 20 2 SW A 145 118* 114* 24 2 SW A 88 96* 802 26 2 EW S 130 96* 85* 27 2 EW S 130 140* 130* 33 2 PLA 110 120 120 36 2 PLA 150 135 122 37 2 SW A >120 110 80 38 2 SW A 100 100 95 44 2 SW A - 125 112 46 2 PLA > 240 230 240 47 2 PLA >220 235 230 52 1 PLA 120 120 125 54 2 PLA >240 200 180 56 2 FOR >180 1205; 120 61 3 FOR 200 189* 167* 66 3 SMA 140 1165; 1165; 67 2 S A M ;125 120 115 68 2 S A M ->125 115 110 69 2 SMA 160 140 130 78 2 FOR 140 115 115 KEY 1 1gCr - %Mo , FOR, F o r g i n g 2 , 2gCr - %Mo PLAY P l a t e 3, 3Cr - 1Mo SAW, Submerged arc weld ESW, E l e c t r o s l a g w e l d SMA, S h i e l d e d metal arc weld > Upper s h e l f n o t a c c u r a t e l y d e t e r m i n e d d u e t o l a c k of d a t a . Thefiguregiven i s t h eh i g h e s ti m p a c te n e r g yo b s e r v e d . *Data r e p o r t e d by nlatcyial o r i g i n a t o r . 55 - . COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • -_____I -I_- A P I PUBL*759 8 2 m 0732270 0087558 7 .# n o m o o o o m o m o m d h m d r l * h l - l b N N o I I I v I l .. I I W .# O O m o o m o o b o d m o o m a * r l r l o r l d rlrl I I I I I .# o o o ô o m m m o o m m m d m m h m 0 r l a m I - l o o m m m o m o m 0 a o h r l o m h m m a r l a rl I I I I O 0 0 ‘ m m 0 0 0 0 0 0 d o Frr o m h m n l r l m o d N m b rlrl PI I I I I 1 m -H O JØ rn 9 r l - al rn rn O u m o o o o o o m O rl a o m m n l * m a n l m m m c) rl rl I I I I JØ W cd a) JØ rl O cd d FI .# mCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ A P I PUBL*757 8 2 0732270 0087557 7 TABLE 17 Comparison of AT(40) from the Unembrittled Condi- tion (U) to the Step-Cooled Condition(E) and the Maximum Embrittlement After1000, 10,000 and 20,000 hr Isothermal Embrittlement Sample T (4 ò .) U-: mo= aTotr_1000( AT(40b-2~~~( J C $ ; No. O F O F OF O F - 1 -15 30 35 50 154 4* -5 110 25 80 239 9 20 70 - 30 5 133 16 10 35 70 75 135 19 19 27 37 5.2 115 20 10 14 34 44 198 26 60 147 16 7 192 240 27 16 71 86 196 111 33 5 10 20 35 173 36 O 5 10 -10 91 37 125 45 70 120 242 43 115 85 105 110 256 44 57 40 80 90 267 46 20 35 40 35 151 47 95 75 85 115 161 54 35 40 70 110 234 56 112 104 194 169 316 59 14 58 83 118 98 62 13 34 24 29 174 63 34 67 77 82 196 65 32 72 112 67 235 67 25 15 80 65 172 68 -35 25 60 . 40 101 69 15 10 5 20 115 78 -10 15 15 20 241 J: Upper shelf is close to 40 ft-lb. J = (Mn 4- Si) (P + Sn) x lo4.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ A P I PUBL*759 82 W 0732270 0087560 5 M TABLE 18 Thermal Cycles and Transition Temperatures from Charpy Specimens Tested Each Stage at of the repeated de-embrittlement experiment 58COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 8 2 W 0732270 0087561 7 m r TABLE 1 9 Heat Treatments Used on 2kCr-lMo I n g o t No. 75 t o ProduceThree S t r u c t u r e s and Three Strength Levels Rockwell B Structure Heat Treatment Hardness Ferrite-Pearlite 87 1700°F f o r 1 h r , Fur- n a c ec o o lt o1 2 0 0 " F , h o l d 2 h r , Water Quench Bainite/Martensite 87 1 7 0 0 ° F f o r 1 h r , Water Quench 1275°F f o r 24 h r , Water Quench Bainite 87 As-received material, de-embrittled1100°F f oh r , r Water Quench Bainite 98 1 7 0 0 ° Ff o r 1 h r , f o r c e d a i r c o o l t o 950"F, Hold f o r 1h r , A i r cool 1 2 7 5 ° F f o r 4 h r , Water Quench Bainite 108 1700°Ffor 1 h r , forced air c o o l t o 950"F, h o l d f o r 1 h r , A i r cool,llOO°F, % hr, Water Quench As-received 87 1750°F f o r 3 h r , Water condition Quench, 1225°F for 4% h r , A i r c o o l . 1100°Ffor15hr 1 2 0 0 ° F f o r 30 h r 1275°F for 16 hrCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLu759 8 2 W 0 7 3 2 2 7 0 0 0 8 7 5 6 2 7 W TABLE 20 Basic d a t a f o r s a m p l e n o . 75 r e h e a t - t r e a t e d t o g i v e t h r e e s t r u c t u r e s a n dt h r e es t r e n g t h levels. The 40 f t - l bt r a n s i t i o nt e m p e r a t u r e sa n d f r a c t u r ea p p e a r a n c et r a n s i t i o nt e m p e r a t u r e s (FATT) f o rt h ed e - e m b r i t t l e d c o n d i t i o n ( O h r ) and a f t e r 1,000, 10,000 and20,000 h r a t 875F are g i v e na l o n gw i t hc h a n g e s ( A ) due t ot h ei s o t h e r m a le x p o s u r e . A minus s i g n i n t h e A columns i n d i c a t e s t h a t t h e steel is de-embrittling. I n it i a 1 T i m e @ 875F 40 f t - l b TT A40 f t - l b TT FATT AFATT Structure Hardness RB (hr) (OF) (F) (F) ("F) O -130 - - 55 - 1,O00 -115 15 - 50 5 QBM 87 1 0 ,O00 20 15O 80 135 20 ,O00 20 15O 90 145 O 75 - 125 - F-P 87 1,000 45 - 30 95 - 30 1 0 ,O00 40 - 35 80 - 45 20 ,O00 35 - 40 90 - 35 O - 85 - - 10 - B 87 1,00045 - 40 40 50 1 0 ,O00 O 85 110 120 20 ,O00 - 25 60 80 90 O -110 - - 35 - B 98 1,000 - 90 20 - 5 30 10 ,O00 120 10 60 95 20 ,O00 20 130 . 80 115 O 170 - 205 - B 108 1, 50 O00 220 250 45 1 0 ,O00 15O - 20 190 - 15 20 ,O00 110 - 60 160 - 45 - KEY : QBM - Quenched B a i n i t e - M a r t e n s i t eS t r u c t u r e F-P - F e r r i t e - P e a r l i t eS t r u c t u r e B - Bainite tructure SCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLX757 8 2 M 0 7 3 2 2 7 0 00875b3 O W G a ÜI O E rn al . . . . . . . C O m r l e h l a 3 m . . . . . . . . N N N m m N m N r l m w b a 3 0 . . . . . . . m w m c n w m w rl U h rl 61COPYRIGHT American Petroleum Institute . -Licensed by Information Handling Services
  • API PUBLm757 8 2 m 0 7 3 2 2 9 0 0087564 2 H i g h e s t Levels of Elements a t o r A d j a c e n t t o t h e Grain Boundaries i n w t % (the readingsgiveninbrackets a r e on t h e l i m i t of r e s o l u t i o n ) i I Element Sample No. P C Cr Mo Ni - CU Sn 3.0 6.0 3.0 (.5) 20 3.0 1.3- -26 2.5 7.1 5.3 (.5) 1.3 4.2 (.5) 43 2.5 4.5 6.5 (.5) (1.1) 3.8 (.2) 56 7.8 7.0 5.0 1.2 1.8 4.0 ,8 63 2.0 8.1 8 . 6- - 4.6 - ~~ ~COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 82 M 0732270 087565 0 4 M TABLE 23 JIC Values Determined as a Function of the Test Temperature for Sample No. 75 in the Unembrittled Condition Test Temperature JIc (OF) 50 > 15O0 100 > 1500* 150 ? 1500 200 1050 927 250 300 700 *Insufficient dataCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • "" " _ _ API PUBLm959 8 2 m 0 7 3 2 2 9 0 0 8 7 5 b b 0 b m Table 24 40 The Fracture Appearance Transition Temperatures,ft-lb 40 Transition Temperatures (FATT, ft-lb TT) and Upper Shelf Energy Values for Isothermal Embrittlement in the Hydrogen-Environment and Air Compared Sample Isothermal FATT 40 ft-lb TT Upper Shelf Environment No. Temp. , F OF OF ft-lb 46 Air 650 - 30 - 55 > 190 46 H2 650 - 25 - 25 > 240 46 Air 875 - 10 - 45 > 240 46 875 40 - * 25 H2 56 Air 650 40 - 30 > 160 56 H2 650 125 10 > 140 56 Air 875 125 - 10 130 56 H2 875 75 - 10 105 59 Air 650 - 15 - 80 > 180 59 H2 650 - 10 - 75 220 59 Air 875 25 - 75 170 59 H2 875 - 10 - 75 180 *Upper 40 shelf lower than ft-lb. > Upper shelf values indicated by means that insufficient specimens were available for the accurate determination of the upper shelf. 64 > ~ - - - " - - . /COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 M 0 7 3 2 2 7 0 00875b7 8 m Table 25 Comparison of the Analytical Chemistries from Various Specimens Taken from Sample 46 No. ~ ~ ~~~~~ ~~ ~ 1,000 hr 1,000 hr 1,000 hr Element As-received exposure in exposure in exposure in air @ 875°F H2 @ 650°F H2 @ 875°F C .ll .12 .12 .12 Cr 2.34 2.35 2.35 2.36 Mo 10 .8 .98 .96 1.00 Mn .43 .45 .44 .46 si .17 .14 .15 .16 Ni .19 .19 .18 .20 Cu .25 .27 .27 .27 P O10 .O17 .O18 .015 S .O03 .O06 .O06 .006 Sn .O15 .O14 .O15 .o13 Table 26 Rockwell B Hardness Measurements from Specimens in the "As-Received" Condition and After Exposure in AirH2and Sample No. Condition 46 56 59 As-received or unexposed I 81 1 I 85.5 I I 86 1 875F for 1,000 hr in air 81.5 91.5 91 . . 650°F for 1,000 hr 82.5 93 91 1 1 1 I in 3500 psig H2 875OF for1,000 hr in 3500 psigH2 72.5 88 83.5COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • "__ A P I PUBL*759 8 2 M 0732270 0 0 8 7 5 b 8 T M h W -x.# .#-x o o m o m o O c n F O O O ou)oooo Cvhlhlmerl O " o O O F e r l d m o h l rlrlrlrlrlrl h l r l r l h l C v r l rlrlrlrlrlrl A rl I I I I I I I II I I O 0 0 O 0 0 O 0 0 O 0 0 O 0 0 O 0 0 ooo, O 0 0 R S W o R"W2;o";o" a 9 w o h 9 o0o rl , , F hl A 66COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 M 0732270 0 0 8 7 5 b 7 L O O O D T 3 9 3 3 03 hl W n a 4 B n a al $4 1 a al $4 3 al u L) *d a v) cd 3 al W 8 W 8 $4 Pi WCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*957 B2 0732270 0 0 8 7 5 7 0 B O YI I x x x I D x x x x x x x x x X xCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Ma 2O Mc ar 5oox Sample N o . 1 Material Key: 2 PIA F i g . 1. M e t a l l o g r a p h i cs e c t i o n s of s a m p l e No. 1 s h o w i n gt y p i c a lb a i n i t i cs t r u c t u r e 69COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm959 A2 0732290 OUA7572 3 M4 a . 2oox Mg a e 500x Sample No. 8 Material Key : 2PLA m . r l g . 2. Metallographic ections s of s a m p l e No. 8 showing t y p i c a l f e r r i t e - p e a r l i t e s t r u c t u r eCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 W 0732270 0087573 3 W e 9: Tolerance ,001 I ¡I Do not u n d e r c u t a t D & DT , DT Da + ,003 Taper from Da . k - D a Pot i s h Da -T I I I I J FIG , 3, STANDARD TENSILE TEST SPECIMEN I ~- 32 FINIS+¡ U N L E S S OTHERWISE SPECIFIED TOLERANCES . UNLESS OTHERWISE SPECIFIED Westinghouse Research Laboratorles 2 PL DEC. 1 3 PL DEC. I ANGLES f .o2 I f.005 1 20.5. 71 P-COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 82 0732270 0087574 5 I 1 120 A A O - O 80 - 40 P A * A A O O -0 O O -40 n 10 0 200 300 J 200 1 I A O 160 120 O A A 80 A O A O O 40 O . A O O I O I I -0 10 200 300 J Fig. 4 . Shiftinthe 40 f t - l b T r a n s i t i o n Temp r a t u r e p l o t t e d as a f u n c t i o n of J - (Mn + Si)(P + Sn) x 1 0 ( a )A f t e rs t e p - c o o l e de m b r i t t l e m e n t (b) A f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n t See T a b l e 1.0.A Weld O P l a t e a n d F o r g i n gCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm757 8 2 m 0732270 087575- 0 7 m Curve 730339-8 FATTE 25 FATTu 20 -100-50 o 50 10 150 200 250 "F Fig. 5 A FATT -25 o 25 50 75 100 15 150 2 OF Fig. 7 F i g s . 5, 6 , 7 . H i s t o r g r a m s of f r a c t u r ea p p e a r a n c et r a n s i t i o nt e m p e r a t u r e si n t h e "as r e c e i v e d " (FATTU) s t e c o o l e e m b r i t t l e d p d @ATT ) and o charge in transition emperature t AFATT respectively or a l l% samples. Welds a r e d e p i c t e d b y h a t c h e $ areas. The d o t s 4 representplateandforgings. 73COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~" A P PUBL*757 8 2 W 0732270 0 0 8 7 5 7 6 7 W Ï Curve 730338-6 C Mn 20I - n 15l - te and - - m al .gings CT E 10l - L O ò z 5 d oI - , O4 .O6 .O8 ..10 .12,14 .16 ..3 .4 .5 . 6 .7 .8 . 9 1.0 %C % Mn Fig. 8 Fig. 9 25 si v) aY 20 1 15 E - v) 0 - P 10- I 1 I I 5- 1 FOR and 1 PLA 0- O .1 96 si Fig. 10 F i g s . 8 , 9, 10.Histograms of c a r b o nm a n g a n e s ea n ds i l i c o nf o r all s a m p l e sr e s p e c t i v e l yf o r a l l samples. Welds are d e p i c t e d by hatched areas a n d t h e d o t s r e p r e s e n t p l a t e andforgings.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*:959 8 2 m 0 7 3 2 2 9 0 0 0 8 7 5 7 7 O m n P Sn 15 -VI al E -m v) O ô 10 æ 5 .o 25 50 75 100 150 125 175 200 225 o 50 100 150 m 250 #x) P in PPM Sn in PPM Fig. 11 ,Fig. 12 30- 25- 25 As Sb -v) al E 20- 20 n C: 15- Y O 1 - 15 g n ò æ - E v) O 10 æ 5 150 2M) W ) #x) 350 400 * o O 10 2030 40 M 60 70 As in PPM Sb in PPM Fig. 13 Fig. 14 F i g s . 11, 1 2 , 13 and 1 4 . H i s t o g r a m s of t h et r a m p elements P , Sn, A s and Sb r e s p e c t i v e l y f o r a l l samples. Welds are d e p i c t e d by h a t c h e d areas and t h e d o t s r e p r e s e n t t h e p l a t e a n d f o r g i n g s . 75 . ~.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Curve 730341-c S N 20 c U $5 1 - E v) O 2 10 5 O o 501001502002M S in PPM N in PPM Fig. 15 Fig. 16 25 J II- II Factor O 20 15 I v) 6 g 10 I I I - ,p I 5 O 1100 lm O 50 1 I 150 200 250 300 350 400 O in PPM (Mn + Si) ( P + Sn) x lo4 Fig. 17 Fig. 18 F i g s .1 5 ,1 6 , 1 7 , 18. Histograms of t h ee l e m e n t s S , N and O and t h e e m b r i t t l e m e n tf a c t o r J r e s p e c t i v e l yf o r a l l samples. The welds are d e p i c t e d by t h e h a t c h e d areas and t h e d o t s r e p r e s e n t t h e p l a t e and f o r g i n g s .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m -0732270 0087577 4 i Sample-No. 1 I 2PLA I Isothermal Embrittlement "Temp, O F 800 725 875 950 1 2; O W+*.- 50 100 40 ft-lb Transition Temp. OF I 950 - Isothermal 875 - Embrittlement Temp, O F 800 - 725 k ..&. " 650 - U I t E?I I 1 100 50 150 fracture Appearance Transition Temp. O F Fig. 19 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 e, 10,000 O , and 20,000 hr X. The bench mark 1. U represents the starting condition and 1 E . the step-cooled embrittled condition. 77COPYRIGHT American Petroleum Institute - .Licensed by Information Handling Services
  • _" API PUBL*757 8 2 ÍI732270 008758- Sample No. 4 I 1 SAW I 950 Isothermal 875 Embrittlement 800 Temp, O F 725 650 I I ~~ ~ ~~ ~~ 100 150 200 I 40 ft-lb Transition Temp. OF c Isothermal 7 Embrittlement 800 - {Q-? Temp, O F 725 - 650 - - UtbE I I I I 100. 150 200 Fracture Appearance Transition Temp. O F Fig. 20 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 9, 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I P U B L * 7 5 9 ~82 m 0732290 0087581 2 m Sample No. 9 I 2PLA 1 r- Isothermal Embrittlement 950 875 800 ! &?<* I Temp, O F 725 o1 - 650 - 73 .U ) I I E t 1 I I -100 -50 O 40 ft-lb Transition Temp. Of: I Isothermal 875 - Embrittlement 800 Temp, O F 725 a 650 -50 O 50 100 150 Fracture Appearance Tran sition Temp. O F Fig. 21 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a functionof the isothermal annealing temperature after 1,000 8 , 10,000 O, and 20,000 hr X. The.bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition. 79 F - >COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*759 8 2 m 0732270 087582 0 L.I m Sample No. 16 c 9% - Isothermal Embrittlement 800 Temp, O F 725 650 -100 -50 O 50 40 ft-lb Transition Temp. OF r 950 Isothermal 875 Embrittlement 800 Temp, O F 725 650 Fracture Appearance Transition Temp. O F Fig. 22 The 40 ft-lb transition. temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O, 10,000 O, and 20,000 hr X . The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ A P I PUBL*757 8 2 m 0732270 087583 0 b m Sample Noo 19 I 2 SAW 1 c 9% - Isothermal 875 - Embrittlement 800 . Temp, O F 725 - 650 - - yj?A I U Ell I I I O 50 100 40 ft-lb Transition Temp. of : Isothermal 950 c 875 Embrittlement 800 Temp, O F 725 650 O 50 100 Fracture Appearance Transition Temp. OF Fig. 23 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O , 10,000 O , and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample NoP 20 L Isothermal 875 Embrittlement 800 Temp, O F 725 650 - 1 U If+E I I I -50 O 50 40 ft-lb Transition Temp. OF Isothermal Embrittlement 800 - Temp, O F I I -50 O 50 Fractu re Appearance Tran sition Temp. OF F i.go 24 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 8 , 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition. 82 .- - .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 8 2 m 0732290 0087585 T m I 2 ESW I Sample No. 26 - 930 - Isothermal 875 - Embrittlement Temp, O F 800 725 - 650 - - I O p50 100 )<e ut I I I I 40 ft-lb Transition Temp. O F c - 950 - Isothermal 875 - Embrittlement 800 Temp, O F 725 - 650 - - < *O* I tI I I 1 50 100 150 Fracture Appearance Transition Temp. O F Fig. 25 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 Q, 10,000 O, and 20,000 hr X. The bench mark .f U represents the starting condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm959 82 m 0732270 087586 0 L m Sample Noo 27 I 2 ESW 1 r Isothermal Embrittlement 800 - Temp, O F I I 1 -50 O 50 40 ft-lb Transition Temp. OF I 2 ESW 1 O r- 950 Isothermal Embrittlement 800 Temp, O F 725 -50 O 50 Fracture Appearance Tran sition Temp. OF Fig. 26 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 Q, 10,000 O, and 20,000 hr X. The bench mark 1 U represents the starting condition and 1 E . . the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 8 2 m 0732270 0087587 3 W Sample No. 33 I2PlA I ,r, - 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 +- -50 U E O 50 I , 40 ft-lb Transition Temp. OF 950 E Isothermal Embrittlement Temp, O F @ìF 875 650 I , * -50 O 50 Fracture Appearance Transition Temp. OF Fig. 27 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O, 10,000 O, and 20,000 hr X. The bench mark 1 U represents the starting condition and 1 E . . the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - . " A P I PUBL*759 8 2 m 0 7 3 2 2 7 0 0087588 5 W Sample .No. 36 x c 950 - Isothermal 875 - Embrittlement 800 - Temp, OÇ 650 - 725 - i I u6 f F 1 I I I -50 O 50 100 40 ft-lb Transition Temp. OF Isothermal Embrittlement Temp, O F 875 - 800 - 725 - 650 - - 950 - I p i, . lU+El I I -50 O 50 100 Fracture Appearance Transition Temp. O F Fig. 28 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 e, 10,000 O , and 20,000 hr X. The bench mark I. U represents the starting condition and I. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm757 8 2 m 0732270 0087587 7 M Sample No. 37 c 950 - Isothermal Embrittlement 800 Temp, O F 725 650 O 50 . 100 150 40 ft-lb Transition Temp. OF r 950 Isothermal 875 Embrittlement 800 Temp, OF 725 650 O150 50 100 Fracture Appearance Transition Temp. OF Fig. 29 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 a, 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and E 1. the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • "~~~ " A P I PUBL*757 8 2 m 0732270 087570 0 3 m Sample Noo 43 c 950 - Isothermal 875 - Embrittlement Temp, OF 800 725 650 - - g"" I u+ I -100 -50 /T O 50 I E 41 I 100 40 ft-lb Transition Temp. O F c 950 - [ Isothermal 875 3 s Embrittlement 800 - & . . d Temp, O F 725 - 650 - - tu I I E 11 I I O 50 100 150 Fracture Appearance Transition Temp. OF Pig. 30 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 Q, 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUflL*757 8 2 3 2 2 7 0 8 7 5 7 3 07 00 5 m Sample No. 44 I 2 SAW I - - 950 Isothermal Embrittlement 800 Temp, O F 725 650 U -100 -50 O 50 100 40 ft-lb Transition Temp. OF [ 2 SAW 1 - 950 - Isothermal 875 7 x:.:% Embrittlement 800 Temp, OF 725 - O 650 - u4 I I I E I I O 50 100 150 .Fracture Appearance Transition Temp. OF Fig. 31 The 40 ft-lb transition temperature-and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 Q, 10,000 o, and 20,000 hr X. The bench mark 1 U represents the starting condition and 1 E . . the step-cooled embrittled condition. . - " 89 T -COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - ~ - A P I PUBL*757 8 2 m 0732270 0087572 7 m Sample No. 46 Isothermal 875 Embrittlement 800 Temp, OF 650 -100 -50 O 40 ft-lb Transition Temp. O f 950 Isothermal 875 Embrittlement 800 -1- Temp, O f 725 650 - I I I -100 -50 o Fracture Appearance Transition Temp. OF Fig. 32 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 9, 10,000 o , and 20,000 hr X. The bench mark I. U represents the starting condition and I. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I P U B L X 7 5 7 8 2 W 0 7 3 2 2 7 0 0087573 7 W Sample No. 47 [ZPLA J c Isothermal. 875 - Embrittlement 800 - Temp, O F I J -150-100 -50 O 40 ft-lb Transition Temp. O F - 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - U 1Et I I I -1% -100 -50 o Fracture Appearance Transition Temp. O F Fig. 33 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 a, 10,000 o, and 20,000 hr X . . The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample No. 54 r 958 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - b I I -150-100 -50 o 40 ft-lb Transition Temp. O f I2PW I r 950 - Is0Itherma1. 875 - Embrittlement 800 - Temp, O F 725 - 650 - A I -100 -50 O 50 100 . Fracture Appearance Transition Temp, O F Fig. 34 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O , 10,000 o, and 20,000 hr X. The bench mark 4 U represents the starting condition and 4 E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*957 8 2 m 0732270 087575 0 2 m Sample No, 56 r 950 Isothermal 875 Embrittlement 800 Temp, O F 725 650 -50 O 50 100 150 40 ft-lb Transition Temp. OF I 2FOR r O 50 100 1% 200 250 Fracture Appearance Transition Temp. OF Fig. 35 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O , 10,000 o , and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample No. 59 2) c 950 - Isothermal a75 - Embrittlement 800 - Temp, OF 725 650 - IU4 4 1 I I J -150 -100 -50 o 40 ft-lb Transition Temp. OF - Isothermal Embrittlement Temp, *F 950- a75 - 800 - 725 - 650 ***O E -50 ..a* d 10 0 P, o 50 , , Fracture Appearance Transition Temp. OFCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~~ A P I PUBL*757 8 2 0732270 0087577 b m Sample No, 62 I 2 SAW 1 - 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - tut f I I I J O . 50 100 40 ft-lb Transition Temp. O f - 950 - p Isothermal 875 - Embrittlement 800 ...a* Temp, O F 725 -. ....*a 650 - - i Ufl fE I l 1 O 50 100 Fracture Appearance Transition Temp. O F Fig. 37 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 Q, 10,000 O, and 20,000 hr X . The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample No, 63 I 2 SMA J Isothermal . 875 Embrittlement 800 .X O Temp, O F 725 o 50 100 40 ft-lb Transition Temp. OF: c I r 950 Isothermal Embrittlement 800 Temp, O F 725 I I 1 O 50 100 fracture Appearance Transition Temp. OF Fig. 38 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 8 , 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services - 96 . -~
  • A P I PUBL*757 8 2 0732270 0087577 T Sample No, 65 I 3 SAW I c 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - d Ø I t U +El 1 I I O 150 50 100 40 ft-lb Transition Temp. OÇ - 950 - O Isothermal 875 - Embrittlement Temp, O F 800 - J$/ II 725 8- 650 - - I "4 ItE I I 1 O 10050 150 200 Fracture Appearance Transition Temp. O F Fig. 39 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O , 10,000 O , and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition. 97COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample No, 67 I 950 - Isothermal Embrittlement 800 Temp, O F 725 650 - I I -50 O 50 100 40 ft-lb Transition Temp. OF - 950 - I sot her mal 875 - Embrittlement 800 - p,p" Temp, OF 650 - 725 - 0px" () I Uft E I I I 1 50 100 150 O Appearance Tran sition Fractu re Temp. *F Fig. 40 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 8 , 10,000 O, and 20,000 hr X. The bench mark 1. U represents the starting condition and 1. E the step-cooled embrittled condition. 98 .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLa757 8 2 W 0732270 0087603 L1 W Sample No, 68 I 2 SMA I c 950 - Isothermal -875 - Embrittlement Temp, OF 800 725 650 - - b I -50 p Efl ¿J O 50 I 40 ft-lb Transition I J Temp.. O F - 950 - Isothermal 875 - "9 Embrittlement 800 - Temp, O F -725- 650 - d i 1 U t 14 E I I 1 O50 100 Fracture Appearance Tran sltlon Temp, O F Fig. 41 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 9 10,000 O, and 20,000 hr X , . The bench mark 1. U represents the starting condition and .f E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~.____._ A P ÏPUBL*959 82 W 0732290 087b02 0 b W Sample No. 69 I 2 SMA 1 c 9% - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - I I I -50 O 50 40 ft-lb Transition Temp. OF I 950 - Isothermal 875 - Ernbrittlement 800 - Temp, OF 725 650 - U I I o 100 fjg Fracture Appearance Transition Temp. O F Fig. 42 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 O , 10,000 O , and 20,000 hr X. The bench mark 1 U represents the starting condition and 1. E . the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 82 m 0732270 087603 0 8 m Sample No. 78 c 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - I 650 - Ertu I I I I O 50 100 150 40 ft-lb Transition Temp. O F IZFOR I - 950 - Isothermal Embrittlement Temp, O F 875 - 800 - 725 - 650 ,- , O FI U4 4 E 50 100 150 I Fracture Appearance Transition Temp. O F , Fig. 43 The 40 ft-lb transition temperature and fracture appearance transition temperature plotted as a function of the isothermal annealing temperature after 1,000 9, 10,000 o, and 20,000 hr X. The bench mark +U represents the starting condition and 1. E the step-cooled embrittled condition.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P L P U B L X 7 5 7 8 2 m 0732270 008760q T m ( a) ( b) v F 1 1 1 1 1 1 10 Unembrittled Step-Cooled Embrittled - v) W E" m v, c O L -5 w n E z æ O -200 -100 O 50 OF -0 10 O 50 150 OF 40 Ft Lb ll 40Ft. Lb ll t l5 I I loo0 Hr Isothermal I I 1 Embrittlement v) = 10 a2 - E m VI O L aJ n E æ 5 = O -100 O 50 1 0 0 OF -50 O 50 150 OF 40 Ft Lb TT 40 Ft Lb ll Fig. 4 4 . H i s t o g r a m so ft h e 40 f t - l bT r a n s i t i o nT e m p e r a t u r ef o rs a m p l e s e v a l u a t e d i n Phase I and II of t h e p r o j e c t . ( a )U n e m b r i t t l e do r "as r e c e i v e d "c o n d i t i o n ( b )S t e p - c o o l e de m b r i t t l e dc o n d i t i o n ( c )A f t e r1 0 0 0h ri s o t h e r m a le m b r i t t l e m e n t ( d ) A f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n tCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 8 2 m 0 7 3 2 2 7 0 0 0 B 7 b 0 5 L m h g . 6427A05 / / / / / I t T + L Width rraverse I ong I/ Fig. 1 ( a 1 Plate: Orientation and designation of samples " l Weldment I I Fig. 45. Schematic of o r i e n t a t i o n of n o t c h e si n Charpyspecimens Phase I: L-S and T-S P h a s e II: L-T and T-LCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*K959 8 2 M 0732290 0087bOb 3 M 0 Curve 726803-8 + Phase I FATT 1501 OF / 40 ft lb T T Phase II Fig. 46 FATT and 40 f t - l b TT d a t af r o mu n e m b r i t t l e da n d s t e p - c o o l e de m b r i t t l e ds p e c i m e n sp l o t t e d SO t h a t t h er e l a t i o n s h i pb e t w e e nP h a s e I andPhase II orientations can be seen.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*759 A2 0 7 3 2 2 7 0 0087687 S 1400 1200 1 &;TENlflZ!NG TEMP1796OE 1000 6 20 REFERENCE NO i08 800 SOLID LINES DIP QUENCH SOO 1 0 IO2 IO" TIME - SECONDS Fig. 47. Cooling r a t e datasuperimposedon A387D c o n t i n u o u s I coolingtransformation diagram. (Taken from R. E . LORENTZ, Jr. Welding J n l . , 2 p 440s .(.1962)).COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • B P I PUBLX757 6 2 0732270 0087608 7 Mag. 200x Mag. 500X F i g , 48 F e r r i t e - p e a r l i t es t r u c t u r ep r o d u c e di ns a m p l e No. 75 f o rt h e structural tudy s a t a h a r d n e s s of = 87. 106 .- ‘tCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLX959 8 2 0 7 3 2 2 7 0 0087607 7 13a( 2 3X Ma 500X F i g . 49 B a i n i t i cs t r u c t u r ep r o d u c e di n slow c o o l e d e a t r e a t m e n t . h This sample vas tempered t og i v e a h a r d n e s s of = 98. ( s e e T a b l e 19) 107COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Isothermal Embrittlement Time, hrs Fig* 50 The 40 ft-lb TT as a function of isothermal embrittlement time for five samples representing the effects of strength level (Rockwell b hardness) and structure Structure Key RB QBM (87) qyenched Bainite-Martensite 87 F-P (87) Ferrite Pearlite 87 B (87) Bainite 87 B (98) Bainite 98 B (108) Bainite 108COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*957 82 m 0732290 0087611 7 m Curve 725980-6 Sample No. 20 S 2 iI O 400 800 P 10 6 rp s1 2 B I , o Cu Fig. 51 The wt % of segregated elements as a function of the distance from the grain boundary derived from the Auger spectra for Sample No. 20 after 20,000 hr isothermal embrittlement. 1o9 1.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBLm959 8 2 m 0 7 3 2 2 9 0 0 0 8 7 b L 2 9 W Curve 725981 -B Sample No. 26 e 4 T P e Cu 5t 10- 8- Mo Cr 6 ,.-- t., - 0"" -0 2- O O I I I O 400 800 1600 o 400 800 1600 Fe Fig. 52 The wt % of segregated elements as a function of the d-istance from the grain boundary derived from the Auger spectra for Sample No. 26 after 20,000 hr isothermal embrittlement. 110 --.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm957 82 W 0732270 0087633 O W Curve 725976-B Sample No. 43 5 2- i 2 3 OO I 400 ! 800 ! P *1600 1) O O t t e 400 4 800 Cu h 1600 A 4 7- 6 Cr Mo . " " A s 45- L < 3- " - "4 I I J 2 I I l O 1600 O 1600 400 400 To 4 F v loor Fe O 400 800 1600 O 400 800 1600 A 4 Fig. 53 The w t % o f s e g r e g a t e d e l e m e n t s as a f u n c t i o n o f t h e d i s t a n c e fromthegrainboundaryderivedfromthe Auger s p e c t r a f o r Sample No. 4 3 - a f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n t . i11COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - - . . ~ ~~ A P I PUBL*359 82 W 0732290 087bLq 0 2 W Curve 725977-0 Sample No. 5r P I Cu l t t t . I & O 400 / 800 1600 A r Cr v O 400 800 1600 O 400 800 1600 A A r 90 Fe / 2t O 400 800 1600 O 400 800 1600 A A Fig. 54 The w t % o fs e g r e g a t e de l e m e n t s as a f u n c t i o n of t h e d i s t a n c e from t h e g r a i n . b o u n d a r y d e r i v e d f r o m t h e Auger s p e c t r a f o r Sample No..56 a f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n t .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 82 m 0732270 0087635 L1 m Curve 725979-B Sample No. 63 5 2- 4- P Cu gP €S 3- 4 3 1- 2t ! l " " L "" O O.r A - a l 4 O 400 800 1600 O 400 800 1600 A A 10 Mo Cr I 60 s &, 81 L. !4 - i 6°K.- -- o - " 5 - -4 4- "" " 2- -v 2- 0, I I l O I I I O 400 800 1600 O 400 800 1600 A A lt- +O .O 400 800 70 1 1600 O 400 800 f 1600 A 8, Fig. 55 The w % o fs e g r e g a t e de l e m e n t s t as a f u n c t i o n of t h e d i s t a n c e from the grain boundary derived from the Auger s p e c t r a f o r Sample No. 6 3 a f t e r 20,000 h r i s o t h e r m a l e m b r i t t l e m e n t . 113 " /-COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • S A P I PUBLx957 8 2 m 0 7 3 2 2 9 0 0087bLb b M i I O Fig. 56 Auger spectrum from Sample No. 56 which been had isothermally e m b r i t t l e d f o r 20,000 h r a t 875F. Note t h ev e r yl a r g e Cu peak on t h e r i g h t - h a n d s i d e .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I P U B L X 9 5 9 B2 m 0 7 3 2 2 7 0 0087637 B 2200 Test Temperatu re MOO o 5OoF 0 100°F o 150QF 0 - 1800 O 2QO°F O O v 250V 1600 D X ° OF O 1400 Al E 1200 7 r - I 1000 800 - 600 200 J 0.3 0.6 0.9 1.2 1.5 1.8 2.1 24 2.7 3.0 Crack Extension, da mm Fig. 57 J versus "a" for the unembrittled specimens of sample no. 75.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 28000 26000 A ”””” 24000 C 22000 , D- F E 20000 18000 16000 14000 12000 10000 8000 6000 4000 t 2000 .O2 .O4 ,O6 .O8 .1 .12.14.16.18 .20.22 2 4 .26 .28 Load Line Displacement/Remaining Ligament 6 / b inlin Fig. 58 Normalized load versus displacement curves for specimens of sample no. 75 tested at various temperatures. Specimen Test Temp. (‘F) A 50 B 100 C 150 D 200 E 250 F 300COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBLm757 8 2 m 0 7 3 2 2 7 0 0087639 I m Sample No.. 46 c 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - U W I J -100 -50 O 40 ft-lb Transition Temp. OF 950 Isothermal 875 Embrittlement 800 Temp, O F 725 650 -100 -50 o F acture Appearance Transition Temp. O F Fig.59 The 40 f t - l b t r a n s i t i o n t e m p e r a t u r e and f r a c t u r ea p p e a r a n c e transition temperature plotted a s a f u n c t i o n of t h e i s o t h e r m a l annealing temperature after 1,000 h r a , 1 0 , 0 0 0 h r O and 20,000 h r X . The bench mark +U r e p r e s e n t st h es t a r t i n g c o n d i t i o n and + E t h es t e p - c o o l e de m b r i t t l e dc o n d i t i o n .F o r comparisonthedatafrom a 3,500 p s i g H2 e n v i r o n m e n t a f t e r 1 , 5 0 0 h r a t 650and 875F are r e p r e s e n t e d b y @ . 117 I . .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*353 82 W 0732230 087b20 0 8 Sample No. 56 950 - Isothermal 875 - Embrittlement 800 - Temp, O F 725 - 650 - . -50 O 10050 1% 40 ft-lb Transition Temp. OF 950 Isothermal 875 Embrittlement 800 Temp, O F 725 650 - U1 I f E l I J O 50 100 150 200 250 Fracture Appearance Transition Temp. O F F i g . 60 The 4 0 f t - l bt r a n s i t i o nt e m p e r a t u r e and f r a c t u r ea p p e a r a n c e transitiontemperatureplotted as a f u n c t i o n of t h e i s o t h e r m a l a n n e a l i n g t e m p e r a t u r e a f t e r 1,000 h r @ , 1 0 , 0 0 0 h r O and 20,000 h r X . The bench mark +U r e p r e s e n t st h es t a r t i n g c o n d i t i o n and +E t h es t e p - c o o l e de m b r i t t l e dc o n d i t i o n .F o r c o m p a r i s o nt h ed a t af r o m a 3,500 p s i g H2 e n v i r o n m e n ta f t e r . 1 , 5 0 0 h r a t 650and 875F a r e r e p r e s e n t e d b y @ .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • Sample No. 59 P" Fig. 61- The 40 f t - l bt r a n s i t i o nt e m p e r a t u r ea n df r a c t u r ea p p e a r a n c e transition temperature plotted as a f u n c t i o n of t h e i s o t h e r m a l a n n e a l i n gt e m p e r a t u r ea f t e r1 , 0 0 0h r , 1 0 , 0 0 0h r €3 and 20,000 h r X . The bench mark +U r e p r e s e n t st h es t a r t i n g c o n d i t i o na n d +E t h es t e p - c o o l e de m b r i t t l e dc o n d i t i o n . For comparison the data from a 3 , 5 0 0 p s i g H2 e n v i r o n m e n t a f t e r 1 , 5 0 0 h r a t 650and 875F a r e r e p r e s e n t e d b y @ .COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - A P I PUiL*757 82 32270 87622 07 00 L A X5 O0 B X500 F i g . 62 Metallographic sections of sample no. 46 (A) in the "as- received" condition and (B) after 1,000 hr at 875°F in air. Etch 2% Nital.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A X500 B X500 Fig.63 MetallographicsectionS.ofsampleno. 46 (A) a f t e r1 , 0 0 0h r at 650°F i n 3,500 p s i g H 2 and (B) a f t e r 1 , 0 0 0 h r a t 875°F i n 3,500 p s i g H z . Etch 2% Nital. 121 , fCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • O O O O vl m N rl x 122 - 8COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*757 A2 0732270 QB87b25 9 V O 8 F Q C O m x .h MCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL8957 8 2 0 7 3 2 2 7 0 0087b2b 7 V O O O W 4 hl xCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • ~ -:A P I . PUËLX357 80 7 3 2 2 9 0 2 OOA4627 O x1500 x5000 Fig. 67 Fracture surface of sample no. 46 after 1,000 hr at 875°F in 3500 psig of H2. The x1500 fractograph shows a combination of cleavage and voids on intergranular facets. The x5000 . fractograph shows detail of voids formed. 125COPYRIGHT American Petroleum Institute . . Licensed by Information Handling Services
  • B P I PUBL8757 8 2 3 2 2 7 0 07 0087628 2 x1500 x5000 Fig. 68 Fracture surface of sample no. 56 after 1,000 hr at 875°F in 3500 psig H2. The x1500 fractograph shows intergranular - fracture and cleavage, The higher magnification shows a detail of the intergranular surface.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 087b27 0 4 m APPENDIX-DISCUSSION OF THE CHARPY TEST (a) Sources of Error in Charpy Impact Test Data The overall interpretation of the data depends to a large extent upon the significance of the numbers derived from the Charpy test. Throughout the program the Charpy testing procedure used at WRDC has been exactly that specified in the ASTM A370 and E23 l 6T Addi- TT19 T, . tionally the Charpy impact testing machine was periodically calibrated by using Charpy standards supplied by Watertown Arsenal. The tests were performed throughout by the same "operator" and the fracture appearances were "read" by the same operator and checked by two independent fracture surface readers. Four major areas which might account for inconsistencies in the Charpy impact curve.data are listed below. o Material o Is the ingot correctly identified? o Is the rolling direction correctly marked? o Is the material chemically uniform? o Have additional heat treatments been introducedktween comparative tests? o Charpy Sample o Is the Charpy bar correctly orientated? o Is the notch inthe Charpy bar correctly orientated? o Is the notch machining consistent from laboratory to laboratory? o Testing o Is there an "operator" variable in testing? o time from bath to time"of impact o temperature of bath o positioning of specimen o Has the Impact Testing Machine been maintained and calibrated? o Data o Is the fracture appearance reading consistent from laboratory to laboratory? o .Are sufficient tests run to reasonably a,ssess Charpy impact curves? o Is there an inconsistencyin defining the best Charpy curve to the data?COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • "P A P I PUBL*757 8 2 m 0732270 0087b30 o m Taking all of these possibilities into account and bearing in mind the large number of samples provided for the program from diverse source, it would almost be remarkable if no inconsistencies occurred. Two of these considerations are discussed in the following sections. (b) The Charpy Specimen Fracture Appearance In 1976, Chicago Bridge and Iron (CB&I) and WRDC compared all aspects of the machining, machining tolerances, testing and "eye-ball reading of percentage brittle fracture of the Charpy test. t was I concluded that in every respect the procedures were identical except for minor differences in the machining. Even so the specimen tolerances were the same. J.E. Bonta of CB&I therefore supplied some SAW samples which had been tested for an independent evaluation of percentage brittle fracture at WRDC. The samples were given to the normal operators to readwi.hout any access to the data generated CB&I. The readings are tabulated belowW ductile). ( Westinghouse CB&I Sample Operator A Operator B Reading 1c 10 5 10 1E 35 15 5 1F 75 30 35 2E 10 10 15 2F 15 10 30 2G 55 20 20 5 2H 15 5 I is immediately obvious that there is significant difference between t a the readings. CB&I supplied the entire fracture appearance temperature data, which compared with the few samples evaluated-at WRDC, showed about lOOoF difference in FATT. The reasonfor the di,fferences was established after inspecting sample lF, which represented extremes in the readings, in the SEM. Figure Al shows schematically the appearance of the fracture surface. Zone A, adjacent to the notch, was found to be dimpled rupture. 100% The "shear lips," Zones C were mixed 50% cleavage and dimples rupture, Zone B in the center of the specimen 35% dimpled rupture mixed with D cleavage, and Zone at the back face of the sample 100% ductile. By conventional eye-ball reading, the apparent percentage of ductile fracture is either + 2C + D, assuming that C a ductile shear lip or A is A + D, assuming C is brittle. The former gives 70% ductile corresponding to the CB&I reading, whereas the latter gives 23% ductile corresponding to the WRDC reading. The correct percentage of ductile fracture derivedfh re o m t table below is approximately 57%. A-2 _"COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 0732270 0087b31 2 m % of % Ductile % Ductile Ar Total in Area Total ea Area Each in Area A 20 100 10. o B 30 35 10.5 47 2c 50 23.5 D 13 100 13.0 57.0% Ductile A similar series of fractographic evaluations was carried outon 25 specimens which had been isothermally embrittled for 20,000 hr, mostly at 875OF. None of these specimens exhibited brittle modes of fractures in Zones, A, C and(Fig. Al), but up to 25% dimpled rupture D was found in the nominally brittle Zone An example is shown in Fig. B. A2. The areas of these zones were carefully measured binocular on a of optical microscope and each zone every specimen was inspected in the of SEM to establish the mode fracture. A simple calculation based upon the percentage of dimpled rupture in the area of B yielded a cor- Zone rected estimate of the amount of brittle fracture in each specimen. A comparison of the two measurements of fracture appearance is shown in Fig. A3 from which it can be concluded that there is a systematic error in the conventional visual readings. If this is the situation, one can only use the impact energy or the lateral expansion curve as a criterion for the ductile-to-brittle transition temperature. The 40 ft-lb tem- perature is an arbitrary criterion and is subject to error only if the 40 upper or lower shelf energy is close to ft-lb. However, if the impactenergy curve is reasonably representation of the fibrosity curve, it would be more rational to use the impact energy corresponding to the average of the upper and lower shelf energies as a measure of the ductile-brittle transition temperature. In the light of the fractographic study it is not too surprising to find that the shifts in the transition temperatures due to temper embrittlement, AFATT and AT(40), were not always equivalent. Since the 40 ft-lb TT is the least subjective of the measurements, it has been used as the primary measure to quantify temper embrittlement in this paper. (c) Experimental Scatter in the 40 ft-lb Transition Temperature 40 Because of differences in the ft-lb TT measured on steel samples at JSW and LJRDC, it was thought that there might be some systematic testing difference between the two laboratories. Sample No. 6 1 (3Cr - 1Mo forging) had sufficient material for four sets of Charpy specimens to be taken out adjacent to one another. Thus variations in material characteristics were eliminated as far as possible. The machining and testing matrix was as follows:COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • - A P I PUBLx959 8 2 0732290 087632 0 4 m Piece Machined Tested 6 1A JSW JSW 6 1B WRDC WRDC - - 6 1C WRDC - JSW 6 1D JSQ - WRDC In this study, all possible variables except machining and (1) ( 2 ) testing apparatus were removed. The combined results are shown in Fig. A4. Here it can be seen that the effect of the notch machining may not be an important factor. Taking the data as a complete set, it can be represented by a broad band as shown in Fig. A4a. However; separating the WRDC and JSW test data reveals two overlapping bands without regard t o origin, Fig. A4b. On this basis it would appear that there is a systematic difference betweenJSW and WRDC Charpy impact the test method. In discussion of this factor the only difference dis- covered was the recorded test temperature. JSW uses the temperature at time to impact where WRDC uses (the conventional) temperature of the bath. If any signifiFant difference resulted from the two methods, the WRDC impact curve should lie above that JSW. In fact, as can be seen of in Fig. A4b, the reverse situation is found. Irrespective of the slight inconsistencies in the data, an estimate of the experimental scatter for this class of steel -(3CR1Mo) can be made. Using the curve in Fig. A4a, the maximum scatter (for the . 30 tests) at the 40 ft-lb TT is approximately +250F. Using the two curves in Fig. A4b, the scatter is +15 to &2O0F. The scatter foundin over 200 Charpy impact curves varied considerably. Typically the plate and forged steels exhibited a scatter fl5oF, whereas in certain weld of steels the 40 ft-lb TT could only be estimated to within k35OF. This is a reflection of the relative homogeneity of plate and weld steel. In order to obtain a better estimate of the transition tem- perature of steels with a large experimental scatter, it would be necessary to increase the number test specimens to form the Charpy of impact curve (i.e. effectively reducing the standard deviation but not the scatter). Unfortunately in this study, the experimental scatter or the approximate standard deviation associated with estimates of the transi- tion temperatures is comparable with the shift in transition temperature due to temper embrittlement in many of the steels assessed. This should be born in mind the interpretation of the data. in At low temperatures theJSW data gives higher impact energy results than WRDC. However, taking the data as a whole, there are30 points uniformly distributed in a broad band. Given that both labora- tories use the same impact testing standard, and that both are competent in their testing techniques, the data shown in Fig.A4 can most reason- ably be interpreted tomean that there is variability the material. inCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • API PUBL*959 8 2 m 0 7 3 2 2 9 0 0 8 7 b 3 3 0 b m In other words, a commercially-produced steel has enough variability in it (i.e. both composition and structure) that large scatter in the data is expected.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • B I I Machined Notch Fig. Al Schematic diagram of the fracture surface of a standard Charpy specimen with approximately50% "brittle" Area B.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • X500 Sample No. 4 : 1 Cr-% Mo Submerged Arc Weld (1 SAW) F i g . A2 The f r a c t u r es u r f a c e shows v e r y clear c l e a v a g ea l o n gw i t h islands of dimpled rupture which appear to be primarily on the grain boundaries.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 0 7 3 2 2 7 0 0087b3b L 80 68 / I / A-8 -. 1COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • A P I PUBL*757 8 2 m 0732270 087637 0 3 m TESTED SYMBO~ JSW JSW a WRC JSW O WRC WRC A JSW WRC A A Test Temperature In O F Fig. A4 Comparison impact of data fromCharpies machined tested and a t Westinghouse Research Center and Japan Steel Works. (a) S c a t t e r band f o r a l l d a t a g a t h e r e d (b) S c a t t e r b a n d s f o r JSW and WRC t e s t e d s p e c i m e n sCOPYRIGHT American Petroleum Institute T -= A-9 ( I)Licensed by Information Handling Services