简介：Thethermalexpansionofworkrollsduringhotstriprollingwasmodeledbyatwo-dimensionaldifferencemethod.Thecalculationmodelwasvalidatedbycomparisonbetweenthepredictionstothemeasuredresults.Withthatmodel,theeffectsofrollingprocessparameterssuchastherollingplan,millpacing,coolantflowrateandsteppedcoolingontherollthermalprofilewereinvestigated.Theresultshowsthatsteppedcoolingofworkrollscanbeusedtocontrolcomplicatedflatnessdefectssuchasquarterbucklesduringhotstriprolling.

简介：AhighalloyedVanadis4(V4)steelwasproducedbysprayformingprocessinBaosteel,andthemicrostructureoftheas-sprayedsteelanditsevolutionduringhotrollingandannealingprocesseswerecharacterized.Itwasfoundthattheas-sprayedV4steelhasahomogeneousandfinescalemicrostructurewithuniformdispersionofcarbides.Thehotrollingtemperatureisthekeyfactorincontrollingtheevolutionoftype,morphologyanddistributionofcarbides,aswellasthematrixmicrostructureoftheas-rolledsteels.Theoptimizedprocessingparametersfortheas-sprayedV4steelarerollingat1050℃andthenannealingat900℃.Themicrostructuralevolutionmechanismsduringhotrollingandannealingaredeterminedaccordingtothemicrostructuralanalyasisofthematerialatdifferentstages.

简介：Inthisstudy,threekindsofdual-phase(DP)steelswereusedtoinvestigatetheinfluenceofsiliconcontentandintereriticalannealingtemperatureontheirmicrostructures,mechanicalproperties,andwork-hardeningbehaviors.Byaddingsiliconandmatchingthecriticalannealingtemperature,anewDPsteel(1.0Siandintercriticallyannealedat790℃)thatexhibitsanexcellentcombinationofultrahighstrengthandadequateductilitywasobtained.Variationsinthestrength,elongation,andfracturemechanismofthespecimenswithrespecttodifferentintercriticalannealingtemperatureswerecorrelatedtomicrostructuralfeatures.Withanincreaseinthesiliconcontent,thereisnosignificantchangeinthemartensiticbandstructureorferritemorphology.Atthesameannealingtemperature,theyieldstrengthandyieldstrengthratioofthespecimensdecreased,butatdifferentannealingtemperatures,thetensilestrengthwasreduced.TheHollomonanalysisresultsindicatethattheworkhardeningbehaviorobeysatwo-stagework-hardeningmechanism.Withanincreasingintercriticalannealingtemperature,the"transitionstrain"shiftstotheleft,andwithanincreasingsiliconcontent,the"transitionstrain"shiftstotheright.Thesurfaceexhibitsductilefracturescharacterizedbyahighdensityofmicrovoiddimples.Withanincreaseinthesiliconcontent,theaveragedimplesizeonthefracturesurfacedecreasesandtheplasticityofthematerialincreases.