简介:Thepurposeofthisresearchistoquantifytheeffectsofcompositionalandprocessingparametersonthemicrostructureandpropertiesofdualphasesteelproduceddirectlybyhotrollingandrapidcooling.Steelswiththebasecompositionof0.1%C,1.4%Si,and1.0%Mnwithadditionsof0.5%Crtoinfluencehardenability,0.04%Nbtoretardrecrystallizationinthelatterstagesofrolling,or0.02%Titoinhibitgraingrowthduringandafterreheatingwereinvestigated.Investigationwasmadetopredictmicrostructureevolutionandtocorrelatemicrostructurewithprocessingparameters.Theeffectsoftheimportantmicrostructureparameterssuchasferritegrainsize,martensitevolumefraction(VM)andmorphology(polygonalorfibrous)onthetensileandimpactpropertiesarediscussed.Multiplelinearregressionanalysisoftheultimatetensilestrengthhasshownthat,increasingVMandmartensitemicrohardnessandgrainrefinementofferritearethemajorcontributionstoincreasethestrengthofthesteel.Itwasfoundthatthedual-phasesteelproducedbycontrolledrollingprocess,withamicrostructurewhichconsistedoffinegrainedferrite(4μm)and35%~40%fibrousmartensite,presentedoptimumtensileandimpactpropertiesbecauseofenhancedresistancetocrackpropagation.
简介:Theinfluenceofthevolumefractionoftemperedmartensiteonmagnetomechanicaldampingoftheferriticmatrixindual-phasealloyswasstudied.Theexperimentalresultsshowedthat(1)dual-phasedampingalloyisofgoodcombinationofstrengthandtoughness:(2)gooddampingca-pacity(Q-1≥5.0×10-3)canbeobtainedindual-phasealloysonlywhenthevolumefractionoftemperedmartensitewascontrolledproperly.Theeffectofmartensiteonmagnetomechanicaldamp-ingoftheferriticmatrixwasanalysed.Thedampingcapacityofdual-phasealloyswasrelatedtothevolumefractionVmoftemperedmartensitebyQ-1=Q-1(1-Vm/1+BVm)atsmallvibrationstrainamplitudesεA≤5.0×10-6.
简介:Thisstudywasconductedtodiscusstheeffectofrollingstrainonmicrostructureandtensilepropertiesofdual-phaseMg-8Li-3Al-2Zn-0.5Y(wt%)alloy,whichwaspreparedbycasting,andthenhomogenizedandrolledat200℃.Therollingprocesswasconductedwith10%reductionperpassandfivedifferentaccumulatedstrains,varyingfrom10%to70%.Theresultsindicatethattheas-castandas-rolledMg-8Li-3Al-2Zn-0.5Yalloysarecomposedofα-Mg,β-Li,AlLiandAl2Yphases.Afterrollingprocess,anisotropicmicrostructurewasobserved.a-Mgphasegotelongatedinbothrollingdirectionandtransversedirectionwiththeadditionofrollingstrain.Consequently,thestrengthofthealloyinbothdirectionswasnotablyimprovedwhereastheelongationdeclined,mainlycausedbystrainhardeninganddispersionstrengthening.Thetensilepropertiesoftheas-rolledalloysintheRD,nomattertheYS,UTSortheelongation,arehigherthanthoseoftheTDduetotheirlargerdeformationstrainandsignificantanisotropyinthehcpα-Mgphase.Inaddition,thefractureandstrengtheningmechanismofthetestedalloyswerealsoinvestigatedsystematically.