An EBSD study of the micro structural development during annealing of a folded super duplex stainless steel sheet sample

(整期优先)网络出版时间:2010-09-24
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Superduplexstainlesssteels(SDSS)showcomplexprecipitationandtransformationbehaviorduringheattreatmentprocesses,whichaffectsbothmechanicalandcorrosionproperties.ThisreportpresentssomedataonthemicrostructuresthatdevelopafterfoldingandsubsequentprecipitationduringheattreatmentofUNSS32750SDSSsheetsamples.ThemicrostructuralandtexturalchangeshavebeenfollowedusingSEM/EBSDtechniques.Uponfolding,bothatextureandstraingradientforminthefolded/bentregion,subsequentheattreatmentat845℃resultsintheferritephasetotransformtosigma,austeniteandchiphases.Transformationwasfoundtobeacceleratedbystrain.Completetransformationoftheferritephaseoccurredwithinhalftheannealingtimerequiredintheunstrainedregions.Thelocalmis-orientationsintheferriteandaustenitephasesreducedduringannealing,however,thereductionintheaustenitewasnotveryhighandasignificantamountremainedevenafterthelongestannealingtime.Thetexturecomponentsthatdevelopedduringthefoldingprocessremainedunchangedevenafteronehourannealingat845℃.TheimplicationofthesefindingscouldhaveabearingontheformationofsigmaphaseduringweldingofSDSSthatmayhaveresidualstressesintroducedduringfinalprocessing.