More Related Content More from MaloNe Wanger (14) 2. Objective
•To acknowledge and understand the fundamental of
corrosion, types and materials standard, design and
practice, application and selection.
•To be able to analyze and trouble shoot the basic
problems of corrosion.
5. ! (Corrosion) # $%'()*+(,+-./0*)1
-2,3+0 45627,!(89$-:(;-#2 5-(= ,+-.!?! 30)',@0A*4
+(5-(5(BA!(C8(*!4(CD2 ,+-.,0(+;-D'9$ /'-+!
A*E$%'(,0(+F);$G!$%'(;5D9HH4( 3IC?,!?D-(5(B
;$G!$%'(;5D *# $%'(C(,('(= ,/0*)94;J!!
( ! ,;*0G ;D'+((;-!5 *# ;*0G 96K
;F(;*0GC8($%'(1 6;F!/' 6;F!F( ((L
*# !?(8
6. 31,I(5-(+)3+04 5CD2;?7!-(5(B31,( !
94;$G! 2 $);C#
( !A!-(=J?#! (Wet corrosion) ( !
$);C!?DF);?7!;5#2 /0*)941+(5;$D'J?#!F(!?(8*#
-(0)0(' ;0G/I90C K;$G!( !C2D;?7!1+-.
$);C/0*)5(CD2-. ;J! (;-!5;*0G ;$G!I4!
( !A!-(=3*4, (Dry corrosion) ( !
$);C!?D ;;!#2 ,F(-(= .N*:5(AJ,4(!C2D-:, ;J! (
!CD2;1;*0G04( ;!#2 ,F(O(6('A!;I(-:,
7. ( !-(5(BF8(3!I(50PN)C(,('(= ,(
! *# I(5I+3$CD25D CQ=0I ( !
( !311-52(8;-5 (Uniform corrosion)
( !A!1;+NF8(;=() (Localized corrosion)
3115*( ((MMaaccrroossccooppiicc ssccaallee))
• ( !3110+(! (Galvanic corrosion)
• (-:E;-D'-+!;F# (Dealloying)
• ( !311*0.5 (Pitting corrosion)
• ( !1;+N6 (Crevice corrosion)
• (;6() (Erosion corrosion)
• ( !F((B:: (Fretting corrosion)
8. 311F.0( (Microscopic scale)
• ( !1;+N 1;! (Intergranular corrosion)
• (3I4(+F(3,;4!30)( ! (Stress corrosion cracking)
• ( !+51+(504( (Corrosion fatigue)
• (3I4(+F(9`/;F! (Hydrogen eemmbbrriittttlleemmeenntt))
9. '
''()**+,-.
$) 14+'-+!-8(EI(,b,I 9$!?D
?+9HH4( $) 1+4' 2 ?+# cathode 30) anode
-)=(!;0# (Salt Bridge) $) 1+4';0# C2D0)0('!?(894D
30)5D9 !1+30)9 !01C2D;0#2 !C2D+4'+(5;G+A0;4D',
!;J! KCl, NH4NO3 C(8*!(4C2DA*94 !F(-(0)0('*!27,
(45@(!9$ D(4,*!27,94
Zn (s ) + 2OH -(aq) ZnO(s) + H 2O(l) + 2e-
11. '
''()**+,-.
/001
012'
(Galvanic cell) galvanic cell ;$G!;600K9HH4(;5DC8(
A*4;)3-9HH4( ;D'+(;600K/+0I( (Voltaic cell) 30);$G!
;#2 ,5# CD2C8(A*4;(30;$0D2'! ;0GI !)*+(,$%'(
6;J!30)DJ!@(!0+I+!8(9HH4( 31,;$G! 2 J!#
/0013-4-' 1. /0013-4- '((PPrriimmaarryy cceellll))
2. /00156'(4-' (Secondary cell)
12. '
''()**+,-.
1. /0013-4-' (Primary cell) # ;600K0+(!J!CD2$%'(;5D
('A!;600KF)A*4@0@0ICD295-(5(B@!01;$G!-(I?,I!494
*# 31195@!01 ,!?!;5#2 ;600;K-#2 5-(=FG)955D
)3-9HH4(9*0 95-(5(B$)F.9H;4(9$A*5 ;J! B(!9Hr('
;600;KJ?# ;=0,
13. '
''()**+,-.
2. /00156'(4-' (Secondary cell) # ;600K0+(!J!CD2$%'(
;5D@!0194 /'(I 9HH4()3-I,F(('! ;600K;4(
-:;600AK!CLC(,01!1CLC(, ,)9HH4(C2D;?7!A!
;600 K;5#2 ;600;K-#2 5-(=-G(5(BC(8A*;4600K01-:-(=;5
9 4;J! 31I;I D-)-59HH4(311I)+2 ;$G!I!4
14. '
''()**+,-.
I+ '(,$%'(D 6KA!;600K0$K+(! $) 1+4' 2 27,;600 K/'
3I0)27,;600FK)$) 1+4'?+9HH4(C2DF.50,9$A!-(0)0(' 3C,
-,)-D30)3C,C ,3,A!;600;K$G!?+9HH4(627,;D'+( ;0G/C
(electrode) ?+C2D;$%'( 6;J! ;D'+( ?+3 /! (anode) 30)
?+C2D;$%'(DJ! ;D'+(?+3/C ((ccaatthhooddee))
$%'( 6;J!CD23 /!
(Zn) Zn(s) Zn2+(aq) + 2e-
$%'(DJ!CD23/C
(Cu) Cu2+(aq) + 2e- Cu(s)
16. '
''()**+,-.
Galvanic series
Element Ion
Electrode Potential
(Volts)
Hydrogen
Overvoltage
(Volts)
Magnesium Mg2+ -1.87 (Base End) 0.7
Aluminium Al3+ -1.35 0.5
Zinc Zn2+ -0.76 0.7
Chromium Cr2+ -0.6 0.32
Iron Fe2+ --00..4444 00..1188
Cadmium Cd2+ -0.4 0.5
Cobalt Co2+ -0.29
Nickel Ni2+ -0.22 0.15
Tin Sn2+ -0.14 0.45
Lead Pb -0.13 0.45
Hydrogen H+ 0.00 -
Antimony Sb3+ +0.11 0.42
Copper Cu2+ +0.34 0.25
Silver Ag+ +0.8 0.1
Gold Au3+ +1.3 (Noble End) 0.35
Oxygen OH- +0.4
Chlorine Cl- +1.36
17. +
'7'- 0
;(-(5(BJ)0 ( ! ,/0*)94/'
1) (;0# AJ4+-. (Material selection)
2) ( 311 (Design)
3) ($1-(=3+04 5 ($1-(=3+0 45 ((MMooddiiffiiccaattiioonn
of environment) 30)(18(.,P(/0*)
4) (;0# 1@+/C(-D (Coating/painting)
5) +QD(C(,9HH4(-;5D (Electrochemical methods)
18. +
'7'- 0
1) (;0# AJ+4-. (MMaatteerriiaall sseelleeccttiioonn))
A!NDCD2I4 ,;J#2 5I /0*) 2 J!CD2I(,! +;0# /0*)CD25D(L'K9HH4(
DJ! (Reduction potential) A04;D',! ;=#2 $4 ,!( !;!#2 ,F(+(5I(,
L'K (Galvanic corrosion)
A!ND ,;*0G04(94-!5CD2AJ4,(!1;+NCD2A04C);0 ;(-(5(B03!+/!45(
;( !311*0.5((PPiittttiinngg)) 9/4';0# AJ;4 331166 C2D@-5/501!52$)5(N
2 % 3C!; 304
A!ND ,;*0G04(94-!5CD2*!(30)I4 ,C8((;J#2 5 ;(-(5(B$4 ,!(
!I(5 1;! (Intergranular corrosion) 9/4';0# AJ;4C2D5D(K1 !I2(8 (95;!
0.03% ;J! ; 316L) *# ;C2D@-5 Ti *# Nb (627,5D+(5-(5(BA!(F11
(K1 !94D+(/;5D'5)
A-AF;#2 ,(;0# AJ40+;J#2 5 ;=#2 $4 ,!( !1;+N ';J#2 5
19. +
'7'- 0
2) ( 311 (DDeessiiggnn))
311A*-4-+!=?!#C2D , (/!I =?!#C2D ,(/QC2D-:,F)0( !
311 Galvanic 94D+(
C8((;0# 1/'(=F(N( '(, 1 1 ;J! 95+C(-D1!/0*)CD2C!( !
! 4' ((aannooddee)) /'95C(-D1!/0*)C2DI(4!C(!( !5(+( (((/Q)) ;!#2 ,F(:
!(;0G (pin-holes) A!1;+NC2DC(-D95-51:NKF)C(8A*;4=?#!C2D (/!!(;0G 3I5D
=?!#(/QC2D!(A*E F7,;$G!(;,( !;r=()1;+NC2D (/!
0(-5@-C(,9HH4()*+(,/0*)I(,J!!;=#2 $4 ,! Galvanic corrosion ;J! AJ4
r!+! (insulator) 2!
AJ4$);G! (Gasket) CD2;$G! ,3G, ;J! ;CH0 !3C!+-.CD2:61 ,;*0+94
20. +
'7'- 0
2)) ( 311 (DDeessiiggnn)) I
311;@ #2A*J4?!,(!A*54D+(5*!(5(?7! *# 311A*J4?!,(!C2D;$G! (/!
-(5(BB ;$0D2'! 6 518(.,94,('
A!NDCD2-,@(! ,;*0+CD25DI) !I(5C /0*) (F=F(N(AJ4I+ ,;=#2 ,
,3G, ;=#2 J+'0(;6()
-(8*1;*0G0(494-!5C2D9-4:E;-D'/;52D'59$A!:$ ,(K91 K((sseennssiittiisseedd)) ;J!
J?!,(!*!(CD2@(!(;J#2 5 ($1$.,/')1+!(C(,+(54 !;=#2 0)0('(K
91KF)-(5(BJ+'$4 ,!( !I(5 1;!94
;(-(5(B0 Stress corrosion cracking 94/'(0+(5;4!;*0# 4(,A!J?!,(!A*4
I2(80, /'( 10('+(5;D'
311+1.5(9*0 ,-(CD2!-,A!C 30)+(0K+A*4;*5()-5 /'8(!7,B7,
:$(,30)0PN)C(,;(NI *# (;=52+(5*!( ,+-.1;+NC2DB:;6()
-:, (Erosion corrosion) ;$G!I4!
21. +
'7'- 0
2)) ( 311 (DDeessiiggnn)) I
AJ4(;J#2 53C!(AJ*45.'?(8 (Rivet) *# -0;0D'+ (Bolt) A!('7+-.
(AJ 4BBoolltt '7/0*) (;J#2 5'7/0*)
(;J#2 5I /0*) 2 J!CD2I(,! +;0# AJ4/0*)CD2AJ4;J#2 5CD2I4(!C(!( !-:,
+(/0*)=?!# (Base metal) C2DI 4,('7I '(,! 4' 1 I+
22. +
'7'- 0
3)) ($1-(=3+0 45 (MMooddiiffiiccaattiioonn ooff eennvviirroonnmmeenntt)) 30)(1(8.,P(/0*)
(AJ-4('1'?,( ! (inhibitor) ;I5A!-(0)0('C2DI 4,(AJ04(8;0D', F;1G
*# AJ4C8((@0I ;=#2 0( ! , .$NK/0*)CD2-5@-
(L7P(B7, CQ=0 ,$FF'C(,-2,3+0 45C2D5DI ( ! ;J! (;$02D'!-(=
F((/Q;$G! (/!A!)11-2,3+0 45I(,b ;$G!I!4
C(8+(5-) ( C(8+(5-) ( I+F- 1 .$NK30)FI) !C2DI(4, '(,-52(8;-5 ;$G!I!4
23. +
'7'- 0
4) (;0# 1@+/C(-D (CCooaattiinngg//ppaaiinnttiinngg))
;$G!($4 ,!95A*;4*0GB:13-O 6;F!30)+(5J?#! 627,;$G!($4 ,!(;
-!5 ,;*0G94 ;$G!+QDCD2-)+ 30)A*4@0DA!($4 ,!(;-!5 3I4 +)+,
A!(;0# 1@+G# I 4,;0# 1 '(,5J (;0# 1@+5D+QD,I 9$!?D
(;0# 1@++4'=0(-I
(;0# 1@+4+'-D
(;0# 1@++4'!?(85!
(;0# 1@++4'(5(8 ;$G!($4 ,!(@. ! ,/0*) D+QD*!27, /'(
;0# 1-(-D8(CD23@!/0*) /'AJ4+(54 !5D4+'!*0('311 ;J! (;0# 1@+;*0G
4+'-,)-D D1. *# D!(;50
24. +
'7'- 0
5) +QD(C(,9HH4(-;5D (EElleeccttrroocchheemmiiccaall mmeetthhooddss))
+QD Cathodic protection /'(C(8A*/4,-4(,C2DI 4,($4 ,!;$G!(/Q 627, (FC(8
/'(A*4)3-9HH4((impressed current) *# (AJ4 (/!-?!;$0# , (sacrificial
anode) /'AJ+4-.I+ #2!627,C(8*!(4C2D;$G! (/!I ;(41/0*)C2DI 4,($4 ,! ;=#2 A*@4.
!3C!
+QD Anodic protection /'(AJ4)3-9HH4(F(('! C8(A*4/0*)CD2I4 ,($$4 ,
-4(,J?!H05KC2D;-BD'(protective film) C2D@+627,F)AJ9441/0*);=D',1(,J! I(,
F( Cathodic protection CD2-(5(BAJ41/0*)94C.J!
25. +
'7'- 0
(;-!5;*0G ;?7!F((C2D;*0G-5@-1!?(8*# 9 !?(8C2D
5D 6;F!0)0(' ' :627,$%'(C2D;?7!#
Fe(s) Fe2+(aq) + 2e-
O2(g) + 2H2O + 4e-2OH-(aq)
627,;5#2 +5$%'((A*340)1 ;0GI !;(4+4'!F)94
2Fe(s) + O2(g) + 2H2O Fe(OH)2(s)
/'@0IN{CK2D94# Fe(OH)2 950)0('!?(8 30)-(5(B;$%'(1 6;F!
I 9$,!?D
4Fe(OH)2(s) + O2(g) + 2H2O 4Fe(OH)3(s)
/' Fe(OH)3 C2D;?7!!?D5D0PN).);$G!:=.!30)5D-D!?(8I(03, 627,:4FC+29$#
-!5;*0G 627,;$G!@0IN{-K.C(4'C2D;?7!F((-7 !
26. +
'7'- 0
Environment
• Nature of the
corrodent
• Operating condition
• Polarization effects
• Electrochemical
Material
properties
activity of material
• Homogeneity
• Passivity
Physical
conditions
• Design
• Stress
• Couples
• External energy
• Mechanical action
29. +
'7'- 0
The corrosion appearances on elements and on base metal
30. +
'7'- 0
MMeettaalllliicc CCoorrrroossiioonn aanndd IIttss PPrreevveennttiioonn
Uniform Corrosion
Galvanic Corrosion
PPiittttiinngg CCoorrrroossiioonn
Intergranular Corrosion
Crevice Corrosion
Erosion Corrosion
Stress Corrosion Cracking
Selective Leaching
31. +
'7'- 0
( !311-52(8;-5 (UUnniiffoorrmm ccoorrrroossiioonn))
( !311-52(8;-5 (UUnniiffoorrmm ccoorrrroossiioonn))
32. +
'7'- 0
( !311-52(8;-5 (UUnniiffoorrmm ccoorrrroossiioonn)) ;$G!( !C2D
;?7!;!#2 ,F(/0*)-5@-1-2,3+0 45/' I((-:E;-D' ,;!?# /0*)C2D1;+N
I(,b F)A04;D',! C8(A*4-(5(B+ I(( !30) 311(18(.,P(
I(5J+,)');+0(94
0.15 --. 6.N0OPO-2O-4.-Q,.2-6+
.R..R
O-7OST'Q727.R,UT V0W-, 7'0PSVQ-
0.15-1.5 --. 6. N0OPO-2O-4.QO-7OS5
Z1,R[
.R
7-(-PO+-.
)+74 T , , 2012 070
0.(2
1.5 --. 6. )-O-
S7OSPT+
33. +
'7'- 0
( !311-52(8;-5 (UUnniiffoorrmm ccoorrrroossiioonn)
($4 ,!30)(349
;0# AJ4+-. #2!CD2;*5()-5+(
AJ-4('1'?, (Inhibitor)
(J.1;0# 1@++/0*)30)(r(1@+/0*)+4'-( #2#2! ((CCooaattiinnggss))
(0+(5I(,L'K (Cathodic protection)
34. +
'7'- 0
( !;!#2#2 ,F(+(5I(,L' K(GGaallvvaanniicc ccoorrrroossiioonn) ;J! ;5#2
/0*) 2 J!C2DI(,!5(;J#2 5I !F);+(5I(,L'K?7! C(8A*;4(
9*0 , ;0GI !)*+(,/0*)C?,- , /0*)C2DI(4!C(!( !94
!4 '+(F);$G! (/! /0*)CD2I4(!C(!( !945(+(C8(*!4(CD2
;$G!(/Q /')1( !?7!7!1-(=-22,3+0 45C2D2D/0*)C?,- ,
-5@- )')*(,F( 'I (( !3110+(!F).!3,CD2-.
1;+NA04 'I )*+(,/0*)C?,- , 30) I(( !F)00,;5#2
)')*(,F( 'I !?!;=25?7!) --+!=?!#C2D ,(/QI =?!#C2D , (
/! (',2--+!,0(+5( +(5.!3, ,( !C2D (/!FG)',2
-:,?7!)
35. +
'7'- 0
( !;!#2#2 ,F(+(5I(,L' K(GGaallvvaanniicc ccoorrrroossiioonn))
=?!#@+3/C!(;0G30)@0=?!#@+
3 /!!(A*EA!( !
;0G!4 '
A!C(,01! (3/C!(A*E 30)
3 /!!(;0G) ( !F).!3,
36. +
'7'- 0
( !;!#2#2 ,F(+(5I(,L' K(GGaallvvaanniicc ccoorrrroossiioonn))
/0*)CD25DL'K9HH4(
I2(8+(F);$G! (/!
30);( !
37. +
'7'- 0
( !;!#2#2 ,F(+(5I(,L' K(GGaallvvaanniicc ccoorrrroossiioonn))
($4 ,!( !5D*0('+QD,!?D
;0# AJ4+-.CD25D( galvanic Series A04;D',!;C(CD2;$G!94
*0D;02D', I(-+! ,=?#!C2D(/Q/ (/! $1A*=4?!#C2DC?,- ,A0;4D',!
AJr4!+!?!A!1;+NC2DAJ/40*)I(,J!!5(-5@-!
AJ-4(;0# 1@+ '(,)5)+, :30(;0# 1@+A* 4'A:!-(=D
;I5-('1'?, ;=#2 0+(5.!3, ,( !
311CD2A*4-(5(B;$0D2'!J?!,(!CD2;$G! (/!94,('
II?,+-.C2D-(5C2D5D(+(5I(,L'!K 4'+(/0*)C?,- , ;=#2 A*;4( !3C!
38. +
'7'- 0
( !;!#2#2 ,F(+(5I(,L' K(GGaallvvaanniicc ccoorrrroossiioonn))
0PN)( !311
GGaallvvaanniicc CCoorrrroossiioonn
39. +
'7'- 0
(@. !;$G!311:07 (PPiittttiinngg CCoorrrroossiioonn)) A!/0*) $5(N/0*)C2DB:
!9$;$G!-+!;0G 3IC8(A*4;+(5;-D'*('945( (I+F- 1C8(94'( 1(,
(+$(: (FF);0GF!3C15 ,95;*G! 3I(4,A!;$G!/=,A*E;F(-(;*I.,!?D
Concentration Cell I(51;+N$);G!AI4*+*5. *# 5.5 1I(, b ;5#2 ;(@. !
-!5*# +IB.3$0$0 5 #2! b F)J+'?!A* 4concentration )*+(, anode 1 cathode
I(,!5(?7! (@. !F)(8;!!9$;$G!F. b 070,9$A!/0*)5(?7!C.CD
;A!!?(8C2D5D chloride ' :5F);1 aluminum *# stainless steel 627,;$G!/0*)C2D
(L' oxide film I(5@+ ;=#2 $4 ,!(@. ! B(4@+ oxide film ;;$G!: /0*)C2DF.!?!G
F)@. !9,4(' ',2B(4 'A:!-(=!?(8!2,*# $5(N 6;F!A!!?(8 G(FF)5D! 4' C(8A*4
;( oxide film ;=#2 $4 ,!@+;$G!9$9J4(4 r)!?! /0*)F) pit ;$G!:9,4('
40. +
'7'- 0
(@. !;$G!311:07(@. !;$G!311:07 ((PPiittttiinngg CCoorrrroossiioonn))
($4 ,!( !311:075D*0('+QD,!?D
95+!8(/0*)CD2; pitting 94,(' *# 5D3!+/!45 '(,J+(F); pitting 9$AJ4@0I
;$G! .$NK/,,(!I+ '(,;J! (;$0D2'!F(;*0G-3I!;0- J! 18 | 8 CD25D
/501D!5 22%% ;$G!;*0G-;I!;0- J! 331166 F)C(8A*4+(5I(4!C(!(; ppiittttiinngg
;=52?7! '(,5(5(' (;I5/0*)/501D!5J+';=52+(5-(5(BA!($4 ,! 627,
;$G!@05(F( passive surface 5D;-BD'(=;=52?7!5(!!2; ,
(AJ-4('1'?, (inhibitiors) 627,# -(;5DC2D;(49$+(,95A* 4,$K) 1*0, ,
$%'(9HH4(;5DA!( !;?7!1B+4!C?, 3 $)( ;I50,9$A!-2,3+0 45C2D
(FF) A*;4 pitting 9,4(' ,!?! corrosion F7,95;?7!
41. +
'7'- 0
(@. !;$G!311:07 (PPiittttiinngg CCoorrrroossiioonn))
TThhee sshhaappee ooff PPiittttiinngg CCoorrrroossiioonn
42. +
'7'- 0
(@. !;$G!311:07 (PPiittttiinngg CCoorrrroossiioonn))
PPiittttiinngg CCoorrrroossiioonn
43. +
'7'- 0
( !I(5 1;( !I(5 1;! (IInntteerrggrraannuullaarr aanndd kknniiffee-lliinnee aattttaacckk)) 5F)
;1 stainless steel Type 18-8 (# /;5D'5 18% !;0 8%) CD2941 heat treatment 5(
95B:I4 , B4( 18-8 Stainless steel B:C8(A*44 !)*+(, 510 | 760oC ;J! A!(;J#2 5;$G!
;+0(!(!= -5+ (;D'+( Sensitization) /;5D'5A!;*0GF)C8($%'(1 carbon ;$G!
chromium carbide II) !5( 'I:(51;+N 1 grain r)!?! $5(N ,/0*)
/;5D'5I(51;+NA0 4b 1 ggrraaiinn F)5D! 4'+($I /'C2D;*0GJ!!?D (L'/;5D'5
;$G!I+$4 ,!(@. ! (;=();;$G! Chromium oxide film $4 ,!@+) B4(I(5 1
grain 5D/;5D'5;5#2 AJ,4(!A!!?(8*# FG);(@. !/' eletrochemical
corrosion cells 9/4'+;G+I(51;+N!?! 1(,(+;!?# ;*0GB7,1 !*0!0,5(;$G!
;50G b +QD$4 ,!G# I 4,;@(;*0GJ!!?DA*44 !B7, 1010 | 1120oC ;=#2 A* 4chrormium
carbide 01#!5(;$G!/;5D'5,;5 304+C8(A*4;'G!@(!J+, sensitization temp (510 |
760oC) /';G+
44. +
'7'- 0
( !I(5 1;( !I(5 1;! (IInntteerrggrraannuullaarr aanndd kknniiffee-lliinnee aattttaacckk))
Chromium carbide
precipitate
Grain boundaries
Cr23 C6
45. +
'7'- 0
( !I(5 1;( !I(5 1;! (IInntteerrggrraannuullaarr aanndd kknniiffee-lliinnee aattttaacckk))
46. +
'7'- 0
( !I(5 1;( !I(5 1;! (IInntteerrggrraannuullaarr aanndd kknniiffee-lliinnee aattttaacckk))
($4 ,!( !311;!5D*0('+QD,!?D
;@(;*0GJ!!?DA*44 ! 1010 | 1120oC ;=#2 A* 4chrormium carbide 01#!5(;$G!
/;5D'5,;5 304+C8(A*4;'G!@(!J+, sensitization temp (510 | 760oC) /';G+
A-/0*) #2!C2D+5I+1(K1 ! ;$G!(K919K4D+(/;5D'5 ;J! NNbb,, TTaa,, TTii A!
$5(N5(= C8(A*495;/5;D'5(K91K
AJ;4*0G-;I!;0-C2D5D$5(N(K1 !! 4'+( 0.03% 627,;(;D'+(;$G!;*0G-;I!;0
-CD25D/0*)CD2B: stabilized ;=#2 $4 ,!$E*( intergranular
($4 ,!30)*0D;02D',$E*( knife-line attack # ( 1;*0G-;I!;0-!?!A*44 !
$)5(N 1065 oC 627,;$G! .N*:5C2D/;5D'5(K910K)0(';(4-:;!?# ;! 3I;
I) !9!/ ;1D'5(K91 K(*# (K91K , Ta, Ti) ?7! C(8A*54D+(5I(4!C(!I C?,
knife-line attack 30) Intergranular Corrosion 311C2+ b 9$
47. +
'7'- 0
( !1;+N6 (CCrreevviiccee CCoorrrroossiioonn)) 5F);1 stainless steel
Type ;$G!:$311 , electrochemical corrosion C2D-(5(B;?7!9A4! '3' '4(+
30)('AI;4()$4 ,!@+C2D627,5D-(0)0(' (!2,) ' :Crevice corrosion 5D+(5-(8E
C(,(4!+L+5 ;5#2 5!;?7!('AI$4);!G rivets 30) bolts 627, ':)*+(, valve disks
30) seats 627, Crevice corrosion ;?7!A!/0*)@-5 ;J! stainless steels 30) titanium,
aalluummiinnuumm 30) ccooppppeerr aallllooyyss
Anode reaction : M M+ + e-
Cathodic reaction : O2 + 2H2O + 4e-4OH-
;5#2 .0$)F.4+'0 9K !
M + Cl- + H2O MOH + H+Cl-
48. +
'7'- 0
( !1;+N6 (CCrreevviiccee CCoorrrroossiioonn))
MMeecchhaanniissmm ooff CCrreevviiccee CCoorrrroossiioonn..
49. +
'7'- 0
( !1;+N6 (CCrreevviiccee CCoorrrroossiioonn))
MMeecchhaanniissmm ooff CCrreevviiccee CCoorrrroossiioonn..
50. +
'7'- 0
( !1;+N6 ((CCrreevviiccee CCoorrrroossiioonn))
($4 ,!( !1;+N6 5D*0('+QD,!?D
AJ4(;J#2 53C!CD2(AJ4 riveted *# botted A!/,-4(,C(,+L+5
311(J!)CD25D:)1(' ;=#2 $4 ,!(-)-5I+ ,-(0)0('
AJ$4);!GC2D95:61-(0)0(' ;J! TTeefflloonn
51. +
'7'- 0
( !+51(;6(( !+51(;6() (EErroossiioonn CCoorrrroossiioonn)) 5F)5DA*;4*G!954(
A!;#2 ,F *# .$NKC2DI 4,AJ41!?(8*# A! ,;*0+C2D5D+(5;G+-:, ;J! A1= ,
;#2 ,-:1!?(8 4;0?D'+ ,C ~0~ (@. !;$G!9$+4';*I. 2 '(,+5! #
electrochemical corrosion Q5( 30)F(3,)3C ,!?(8*# @, #2! b C2D5(1!?(8
/0*)1(,J! (FF)C!1-(=!?(8!2,94D ;=()5D oxide film ;?7! 3I;5#2 'A:!-(=
!?(89*03,*# 5D3,)3CI(, b ooxxiiddee ffiillmm F)B:C(80('9$ /0*)FG)@. !/';G+
+QD$4 ,!G# I4 ,;0# /0*)/'I+F- 1+(5,C! ,5!A!-(=CD25D(
;0#2 !9*+F, b
52. +
'7'- 0
( !+51(;6(( !+51(;6() (EErroossiioonn CCoorrrroossiioonn))
53. +
'7'- 0
( !+51(;6(( !+51(;6() ((EErroossiioonn CCoorrrroossiioonn))
($4 ,!( !+51(;6()5D*0('+QD,!?D
;0# /0*)/'I+F- 1+(5,C! ,5!A!-(=CD25D(
;0#2 !9*+F, b
311)11C ;=#2 *0D;02D', ttuurrbbuulleennccee,, ccaavviittaattiioonnss
;0# 1C 4+'+-.CD2C!(;6()
54. +
'7'- 0
(3I4(+F(( !30)+(5;4(3I4(+F(( !30)+(5;!4(SSttrreessss CCoorrrroossiioonn CCrraacckkiinngg)) ;$G!@0
, corrosion +51 stress A!;!?# /0*) Stress 5D 2 311 # Stress ('! C2D)C(81
/0*);!#2 ,F((AJ,4(! 30) Stress ('A!;!?# /0*);!#2 ,F((?7!:$/0*)*# (
;J#2 5 Stress Corrosion 5;25F( corrosion C2DF.AF.*!27,1!@+/0*)311 pitting 627,F)
;$G!F.;25I!4 , Stress Corrosion C2D!4 , pit F)5D stress ;=52?7!5( F!C(8A*/40*)
3' F(!9 4/0*)FG)(I 9$ D/';G+
Tensile stress
Corrosive
environment
Susceptible
material
(Alloy)
Environmentally Induced Cracking
EIC
55. +
'7'- 0
(3I4(+F(( !30)+(5;4(3I4(+F(( !30)+(5;!4(SSttrreessss CCoorrrroossiioonn CCrraacckkiinngg))
56. +
'7'- 0
( !+51(;6(( !+51(;6() ((EErroossiioonn CCoorrrroossiioonn))
($4 ,!( !+51(;6()5D*0('+QD,!?D
( 1/0*)CD2 .N*:5-:, ;=#2 0('+(5;D' 30)0 stress A!
;!?# /0*)0, (Stress Relief)
0+(5.!3, ,-2,3+0 45/' 1/0*)!?! ;J! 0 .N*:5
0+(5;54!4 ,-( 30)(AJ-4('1'?,
57. +
'7'- 0
(@. !311;0# (SSeelleeccttiivvee lleeaacchhiinngg oorr DDeeaallllooyyiinngg) F);1/0*)@-5C2D
Q(I.*!27,;-BD'+( DQ(I.*!27,;5#2 -5@-11'((L ;J!
(@. !311 Dezincification ,C ,;*0# , (C ,3,@-5-,)-D) CD2-,)-DF)B:
0)0(' 9$ ;*0# 9+;4*0# 3IC ,3,C2D;$G!:=.! 627,35+4(:$C,F);*5# !;5 3I+(5
3G,3,F)00,
Graphitization ,;*0G*0 ;C( # (@. !C2D;?7!;!#2 ,F(;*0G ( (/!) @.
!9$ ;*0# I(('(9HIK0PN)3@! (Graphite flake) CD2;$G!(/Q9+4 C8(A*4
/,-4(,;*0G*0 ;C(-:E;-D'+(53G, (34$E*(C8(/'(AJ4;*0G*0 (9HIK
05 *# ;*0G*0 1;*!D'+ (Malleable cast iron) 3C!
58. +
'7'- 0
(@. !311;0# (SSeelleeccttiivvee lleeaacchhiinngg oorr DDeeaallllooyyiinngg)
Graphitic corrosion of a gray cast iron valve
Micrographic appearance of a
dezincification of brass.
Plug Denickelification of 70-
30 Cu-Ni
Plug Dezincification of
Admiralty Brass
59. +
'7'- 0
(@. !311;0# (SSeelleeccttiivvee lleeaacchhiinngg oorr DDeeaallllooyyiinngg))
($4 ,!(@. !3115D*0('+QD,!?D
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/0*) (Metal)
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= 0;5 K (Polymer)
+-.@-5 (Composites)
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Yield strength 275 MPa
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