TRIP780高强钢动态变形行为的宏微观研究

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1、上海交通大学硕士学位论文TRIP780高强钢动态变形行为的宏微观研究姓名：史文超申请学位级别：硕士专业：车辆工程指导教师：李大永20090201上海交通大学硕士学位论文摘要行了对比，考察高强钢在碰撞过程中的力学行为和吸能特性，评估材料的使用特性。研究结果表明：TRIP780高强钢是一种兼有高强度和高塑性的应变率强化特性的汽车用钢，具有良好的碰撞吸能潜力；所建立的率相关本构模型实现了对TRIP780钢力学行为的准确描述。关键词：相变诱发塑性、动态变形、残余奥氏体、率相关本构方程，冲击过程模拟上海交通大学硕士学位论文ABSTRACTStudyonMacroscopicandM

2、icroscopicDynamicDeformationBehaviorofTRIP780HighStrengthSteelABSTRACTTRIPsteelisanewtypesteel,andischaracterizedbyitsTransformInducedPlasticityproperty.Usually,TRIPsteelhasamulti-phasemicrostructureunderroomtemperature，whichconsistsofferrite(F),bainite(B)andretainedaustenite(Ar).Theretai

3、nedausteniteisunstable,andwilltransformintomartensiteundercertainplasticdeformationconditions.Thenew-bornmartenitehasabetterhardeningpropertycomparingtotheformeraustenite,whichincreasesthedeformationcapabilityandcontributestoplasticitypropertyofthematerial.Thisthesisfocusedonmechanicalpro

4、pertiesoftheTRIP780steelproducedbyBaoshanSteelCompany.Experimentswerecarriedoutbasedonbothmacroscopicandmicroscopicmethods.ThedynamicmechanicalpropertiesofTRIP780steelwerestudiedthroughthestudyontensiletests,metallographicmicrostructureobservation,andXRDmeasurement.Astrainratedependentmat

5、erialconstitutiveequationwasdevelopedandintroducedintothenumericalsimulationofdynamicdeformationduringimpactprocessesofhighstrengthsteelcomponents.第III页上海交通大学硕士学位论文ABSTRACTFirstly,thestaticuni-axialtensileexperimentandthedynamicuni-axialtensileexperimentunderfourdifferenttensilespeeds(0.1

6、5m/s，4m/s，10m/sand15m/s)werecarriedout,thenthestress-straincurvesundervariousstrainrateswereobtained.Throughtheanalysisonthemicrostructureneartothefracturesurface,theTransformInducedPlasticityeffectwasinvestigated.Then,throughtheXRDexperiment,themajorfactorswhichhaveimpactsonthetransforma

7、tionofretainedaustenitewerediscussed.Johnson-Cookmodelwasemployedtodescribetherate-dependentdeformationbehavioroftheTRIPsteel.BasedonthemacroscopicandmicroscopicresearchofdynamicdeformationofTRIP780,astrainratedependentmaterialconstitutivemodelwasdeveloped.Theconsti