简介:13kindsofironores(6fromAustraliaand7fromBrazil)werestudiedontheirpropertiesconcerningCW(CombinedWater)decomposition,Fe2O3decompositionandsoftening-meltinginairatmospherethroughthecharacterizationmethodofTG-DSC(Thermogravimetry-DifferentialScanningCaloremetry).TheexperimentalresultsoftheAustralianoresandBrazilianoresdifferintermsoftheinitialtemperature,temperaturerangeandendothermicamountofCWdecomposition,andbesides,thecontentofCW.ItisestimatedthatforeverypercentincreaseofCWcontentinsinteringrawmaterial,theextrathermalamountabsorbedintheprocessisabout1.83×104kJ,whichequalstothethermalcapacityof0.625kgofstandardcoalburningupcompletely.AstothedecompositionofFe2O3,theinitialtemperatures,terminaltemperaturesandtemperaturerangesoftheAustralianandBrazilianoresarequiteclose.However,theendothermicamountofFe2O3decompositionofthetwoturnsoutratherdifferent:theendothermiccapacityofFe2O3decompositionoftheAustralianoresisgreaterthanthatoftheBrazilianores.Furthermore,theliquidamountgeneratedinthesoftening-meltingprocessiscloselyrelatedtotheSiO2contentinironore.ThehigherSiO2contenttheorecontains,themoreliquidvolumeitwillgenerateinthesoftening-meltingprocessofironore.
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:Superduplexstainlesssteels(SDSS)showcomplexprecipitationandtransformationbehaviorduringheattreatmentprocesses,whichaffectsbothmechanicalandcorrosionproperties.ThisreportpresentssomedataonthemicrostructuresthatdevelopafterfoldingandsubsequentprecipitationduringheattreatmentofUNSS32750SDSSsheetsamples.ThemicrostructuralandtexturalchangeshavebeenfollowedusingSEM/EBSDtechniques.Uponfolding,bothatextureandstraingradientforminthefolded/bentregion,subsequentheattreatmentat845℃resultsintheferritephasetotransformtosigma,austeniteandchiphases.Transformationwasfoundtobeacceleratedbystrain.Completetransformationoftheferritephaseoccurredwithinhalftheannealingtimerequiredintheunstrainedregions.Thelocalmis-orientationsintheferriteandaustenitephasesreducedduringannealing,however,thereductionintheaustenitewasnotveryhighandasignificantamountremainedevenafterthelongestannealingtime.Thetexturecomponentsthatdevelopedduringthefoldingprocessremainedunchangedevenafteronehourannealingat845℃.TheimplicationofthesefindingscouldhaveabearingontheformationofsigmaphaseduringweldingofSDSSthatmayhaveresidualstressesintroducedduringfinalprocessing.