简介:Itisofgreatimportanceforobtainingtheperfectweldingpropertiestocontroltheacicularferrite(AF)transformationbehaviorreasonablyinsteelweld.AFcontinuoustransformationkineticsintheHSLAsteelweldwascalculatedandmodeledbasedonthedirectgrowthontheinclusionsinertinterface.Thesimulationresultsarecoincidentwiththeexperimentalvaluewell.
简介:Themechanicalproperties,creepdamage,creeprupturestrengthandfeaturesofinterfacialfailuresofweldedjointsbetweenmartensite(SA213T91)andpearlitesteel(12Cr1MoV)havebeeninvestigatedbymeansofargontungstenpulsedarcwelding,hightemperatureacceleratedsimulation,creeprupture,mechanicalpropertytestsandscanningelectronicmicroscope(SEM).Theresearchresultsindicatethatthemechanicalpropertiesofovermatchedandmediummatchedjointdeteriorateobviously,andtheyaresusceptibletocreepdamageandfailureafteracceleratedsimulationoperation500h,intheconditionofpreheat250℃,andpostweldingheattreatment750℃×1h.However,themechanicalpropertiesofundermatchedjointarethebest,theinterfacialfailuretendencyofundermatchedweldedjointislessthanthoseofmediumandovermatchedweldedjoint.Therefore,itisreasonablethatlowalloymaterialTR31isusedasthefillermetalofweldbetweenSA213T91and12Cr1MoVsteel.
简介:Anewhardfacingprocess,reactivebrazecoatingprocess(RBCC)wasstudied,and(TiC+Cr3C2)/FecompositecoatingswerepreparedbyRBCCusingcarbon,Cr3C2,iron,ferrochromiumandtitaniumpowderastherawmaterialsinvacuumbrazefurnace.TheresultsshowthatTiCisin-situsynthesizedinthecoatings.ThemethodsofintroducingCr3C2havegreateffectsonthedistributionofTiC.AddingCr3C2directlytotherawmaterialsforcoatings,fineTiCparticlesaggregateintodiscoidsparalleltothecoatingsurface,whereas,in-situsynthesizingCr3C2incoatings,theaggregationsofTiCarelumpish.Duringbrazecoating,Cr3C2particlesdirectlyaddeddissolveandprecipitatetobecomeneedle-shaped.Thecoatingshaveanevenandsmoothsurfaceandarecombinedwiththeirmildsteelsubstratesbyametallurgicalbonding.
简介:Theeffectofnonmetallicinclusionsinthedropletofthestainlesssteelcoveredelectrodeontheporositywasresearched.Theresultshowsthatthenonmetallicinclusionsinthedropletarespherical,theircompositionisdifferentfromtheoneofslagandtheinclusionshavethecharacterof"innerformation".Whentheratioofrutiletoilmeniteinthecoatedmaterialisincreased,thedropletbecomescoarse,thecontentofnonmetallicinclusioninthedropletdecreases,andtheporositysensitivityintheweldmetalalsodecreases.Whentheratiooffledspartoilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusioninthedropletincreases,andtheporositysensitivityintheweldmetalincreases.WhentheratioofFe2O3toilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusiondecreases,whiletheporositysensitivitydoesnotreduce.
简介:EffectsofalloyelementsonthemicrostructureandcrackresistanceofFe-C-Crweldsurfacinglayerwereinvestigated.Theresultsshowthatmicrostructuresofthelayermainlyconsistofcarbidesandaustenitematrix.IncreasingCandCrcontentsimpairthecrackresistanceofthelayerduetoincreasedamountofbrittlecarbides.TheadditionofNi,NborMoimprovesthecrackresistanceofFe-C-CrweldsurfacinglayerbyincreasingtheamountofausteniteandformingfineNbCorM7C3carbidesinthelayer.But,theexcessiveNb(>2.50wt%)orMo(>1.88wt%)impairsthecrackresistanceofthelayer,whichhasrelationwithincreasedcarbidesorcarbidecoarseningandaustenitematrixsolidsolutionstrengthening.ThepropercombinationofC,Cr,Ni,NbandMocanfurtherimprovenotonlythecrackresistanceofFe-C-CrweldsurfacinglayerbutalsotheerosionresistanceasaresultoffineNbCandM7C3carbidesdistributinguniformlyinaustenitematrix.Theoptimallayercompositionsare3.05wt%C,20.58wt%Cr,1.75wt%Ni,2.00wt%Nband1.88wt%Mo.
简介:ButtjointsofQCrO.8/1Cr2lNiSTiequal-thicknessdissimilarmaterialswereobtainedbyelectronbeamweldingwithfixedacceleratingvoltage60kVandfocuscurrent1.99A,changedelectronbeamcurrentandweldingvelocity.MicrostructureandcompositionoftheEBWjointwereinvestigatedbymeansofopticalmicrographyandEDXanalysis,mechanicalpropertiesofthejointwerealsotested.Theresultsshowthatjoint'smacrostructurewasdividedintothreezones:topweldzonenearQCrO.8andbottomweldzoneconsistingofCu(ss.Fe)withacertainamountofdispersedlydistributed(α+ε)mixedmicrostructure,middleweldzoneconsistingof(α+ε)microstracturewithasmallamountofCu(ss.Fe)particles.MorphologicalinhomogeneousmacrostructureandunevenchemicalcompostionofQCrO.8/1Cr21NiSTijointbyEBWarethemostimportantfactortoresultindecreasingjoiningstrength.