简介:Inthisstudy,metallographicanalysisandnanoindentationcharacterizationwereusedtoanalyzethepropertiesandmicrostructuresofas-castnitrogenalloyed27Cr-7Ni-4Mosuperduplexstainlesssteel(super-DSS).Theas-castmicrostructureofthesuper-DSSwascharacterizedbyitsferriteandisland-likeaustenitephases.Duringthesolutionannealingprocess,theaustenitevolumepercentageofthesteeldecreasedgraduallywithincreasedannealingtemperature.Asamainelement,thechromiumcontentintheferriticandausteniticphaseselevatedslightlyatfirstthendecreasedwithincreasedannealingtemperature.Thechromiumpartitioncoefficientinthesteelvariedbyaround1.0.Thecontentsofnickel,anothermainalloyelement,alsoincreasedintheferriticandausteniticphaseswithincreasedannealingtemperature,asdidthenickelpartitioncoefficientinthesteel,whichtendedtobecloseto1.0.Thenanoindentationcharacterizationresultsindicatethatthehardnessoftheaustenitephaseisslightlygreaterthanthatoftheferritephase.Theyweresimilartoeachotherwithinacertaintemperaturerangefrom1050℃to1100℃.Thistemperaturerangewasconsistentwiththetemperaturerangeinwhichthecontentratioofthetwophaseswascloseto1∶1.WefoundtheYoung'smodulusoftheferritephasetobegreaterthanthatoftheaustenitephase.Withincreasedannealingtemperature,theYoung'smodulusoftheferritephasedecreasedwhilethatoftheaustenitephaseremainedalmostunchanged.
简介:Themechanicalandcorrosivepropertiesof00Cr13Ni4Mo(S13-4N)weretestedandcomparedwiththoseof00Cr13Ni6Mo(S13-6).Theeffectsofnitrogenonthepropertiesofthesteelswereanalyzed.Theresultsofthetensileandcorrosiontestsshowthestrength,theductility,andthepittingcorrosionresistanceofS13-4Narehigher,lowerandpoorerthanthoseofS13-6respectively,whentemperedatatemperaturebelow550℃andviceversawhenthetemperingtemperatureishigherthan550℃.TheresultsoftheX-raydiffraction(XRD)andtheelectronbackscattereddiffraction(EBSD)analysesrevealthatinversedausteniteappearsat550℃andtheamountofitpeaksat600℃withthebestductility.AndthetotalamountoftheinversedausteniteinS13-6ismorethanthatinS13-4Nindifferentforms.Nitrogenperformsbetterintermsofstabilizinginversedaustenitewhilenickelismorefavorableforforminginversedaustenite,theamountandstabilityofwhichaffecttheductilityremarkably.ThereasonfortheembrittlementofS13-4Nat450℃canbetheresultofcarbideandnitrideprecipitatingatgrainboundaries.