The sensitivity to cracking of Inconel 600 widely depend on the environmental factors like temperature, level of tensile stress, deformation rate, availability of hydrogen gas, solution pH value.

1. Behavior of highperformance nickel alloys in vigorouschemical media
One of the largestgroupsof nickel basedalloysisNi-Cr-Fe-MoalloysthatcoversInconel 600,Incoloy
825, Incoloy 800 ad HastelloyG30. As Inconel 600 is usedtodevelopthe tubesof steamgenerators
innuclearpowerplants,itisone of the most commonnickel alloysstudiedforitsstresscorrosion
cracking behaviourparticularlyinhotwaterandcaustic solutions. Inconel 600alsoexperiencestress
corrosioncrackingin hightemperature pure waterduringinservice aswell asinlab.Consideringits
significance inthe nuclearplants,the stresscorrosioncrackingof Inconel 600 in pure waterand in
causticsolutionshasbeenwidelyresearchedoverthe decades.
The sensitivitytocrackingof Inconel 600 widelydependonthe environmental factorslike
temperature,levelof tensile stress,deformationrate,availabilityof hydrogengas,solutionpHvalue,
electrochemical potential andmetallurgical factorslike presence of nominal alloyingelements,
magnitude of coldworkand heatprocessing.CrackinginInconel 600 ismainlyintergranularin
nuclearplants.Insome conditions,crackingcanbe transgranulartype.
Incoloy800 isusedin nuclearpowerproduction.Insteamgeneratorapplications,incoloy800 is
more resistanttocracking as compare to Inconel 600, due to moderate nickel concentration.
PrecipitationhardenedhighstrengthIncoloyX750isusedinnuclearreactor internals,primarilyas
fasteners.SimilartoInconel 600, IncoloyX750 issensitivetostresscorrosioncrackinginhigh
temperature waterusuallyusedinnuclearreactors.IthasbeennoticedthatIncoloyX750 could also
be prone to hydrogenembrittlementattemperaturesbelow150oC.Identically,lowtemperature
hydrogeninducedcrackingisalsostudiedforInconel 718.
Incoloy825 offershigherresistancetostresscorrosioncrackinginchloride solutionsascompare to
stainlesssteel grade 316 because of highernickel concentrationinalloy825. U bendtestshave
shownthat INcoloy825 was prone to transgranularstresscorrosioncrackingin45% MgCl2 solutions
at temperaturesabove 146oC.Incoloy825 is widelyusedinthe oil andgas productionin sourwells,
althoughthe functionof othernickel alloyslike HastelloyC276 isstill superiortoIncoloy825. The
nickel alloysare widelyusedincoldprocessedconditionforhighstrength.Environmental factors

2. that may affectthe stresscrackingfunctionof Incoloy825 inoil and gas wellsinclude temperature,
chloride concentrationandavailabilityof hydrogensulfidegas.