简介：TheinfluenceofTiandNbonthemicrostructure,mechanicalproperties,andsecond-phaseprecipitationof430ferriticstainlesssteelwasinvestigated.Inadditiontoopticalmicroscopy,transmissionelectronmicroscopyandX-raydiffractionanalyses,tensiletests,andcarbonitrideextractionexperimentswereconductedtoinvestigatethemicroscopicmechanisms.TheresultsshowedthattheprimaryprecipitatesinSUS430ferriticstainlesssteelwereCr23C6,Mn23C6,andCr7C3,andtheprimarystrengtheningmechanismwasprecipitationstrengthening.WhenTiwasaddedseparately,themainprecipitateswereTiCandTiN.However,coarseTiCadverselyaffectedthemechanicalpropertiesofsteel.Whendouble-stabilizedwithTiandNb,coarseTiCwasreplacedbyfineNbC.Thetypeofprecipitationwasaltered,andprecipitationandsolidsolutionstrengtheningoccurred.Therefore,thetensilestrengthandplasticstrainratio（r-value）improvedto433.60MPaand1.37,respectively.

简介：Themartensitic/ferriticsteelshavebeenusedasboilerandturbinematerialsinpowerplants,andalsobeenselectedaspotentialmaterialsforstructuralmaterialsinnuclearreactors.Inthispaper,thekineticanalysisofthemartensiteformationandmicrostructuralcontrolofhigh-Crmartensitic/ferriticsteelsarereviewed.Amodularapproach,incorporatingFisherpartitioningnucleationandanisotropicgrowthforimpingement,wasproposedtodescribethemartensiteformationkineticsunderdifferentcoolingrates.Thekineticanalysissuggestedathermal-activatedgrowthfeatureoccurringduringthemartensitictransformationofmartensiticsteels.Themicrostructurecanbetunedbycompositionoptimizationandvariouscombinationsofheattreatmentparameters(temperature,time,severeandminordeformation).Fortheapplicationinpowerplant,thepotentialofboundary-design,refinementoforiginalaustenitegrainsizeandthefinalmartensiticlath,pinningeffectofstablecarbides,inimprovingtheperformancesofmartensitic/ferriticsteelsatelevatedtemperaturesshouldbeinvestigatedmorethoroughly.Furthermore,effortsshouldbemadetoexploretheeffectsofretainedausteniteontheimprovementofhigh-temperaturecreepstrength.Fortheapplicationofnuclearplants,attemptsshouldalsobemadetoproduceFepowderswithuniformlydistributedoxideparticlesbychemicalreactions.