钢材种类和变形的基础知识.pptVIP

钢材种类和变形的基础知识

Contents1.SteelMechanicalpropertiesWorldwidesteelgradesAdvancedhighstrengthsteel(AHSS)2.PlasticmechanicsSheetdeformationmodesForminglimitsYieldcriteria2

Introductiontoelasticityandplasticity固体材料受外力作用产生变形，从变形开始到破坏一般要经历两个阶段：弹性变形(elasticdeformation)和塑性变形(plasticdeformation)。外力卸载后，弹性变形能够完全消失，而塑性变形不能消失。弹性变形和塑性变形的机理：材料原子之间的作用力平衡。位错(dislocation)理论。强化机制(workhardeningmechanism)。Dislocationmovement3

UniaxialtensiletestGB/T228金属材料室温拉伸试验方法EN10002-1Metallicmaterials-Tensiletest-Part1:testmethod(inambienttemperature)Typicaltensiletestpiece4

Engineeringstress-straincurve5

Engineeringstress-straincurve6

StrengthandDuctilityStrengthparametersEngineeringstressEngineeringstrainElongationReductionofareaDuctility7

Truestress-straincurveTruestressTruestrain8

Workinghardening(strainhardening)Strainhardeningexponent(n-value)9

Influenceofstrain-hardeningexponentn3n2n110

Anisotropy(R-value)Widthstrain:εw=ln(w/w0)Thicknessstrain:εt=ln(t/t0)R=εw/εtPlanaranisotropyratioNormalplasticanisotropyratio11

StrainratesensitivityStrainrateStrainratesensitivityexponentStrainratesensitivityhasacrucialinfluenceontheresearchofcrashresistanceandhigh-speedstampingformability.12

Worldwidesteelgrades13

Worldwidesteelgrades14

CommonsteeltypesandevolvingAHSStypesInterstitialfree(IF)steelsMildsteelsBakehardenable(BH)steelsIsotropic(IS)steelsCarbon-manganese(CM)steelsHigh-strengthlow-alloy(HSLA)steelsDualphase(DP)steelsTransformationinducedplasticity(TRIP)steelsComplexphase(CP)steelsMartensitic(Mart)steels15

Strengtheningmechanism16

HSLAsteel17

GradesofHSLAsteelinEU18

ApplicationofHSLAsteel19

Dualphase(DP)steel20

EUsteelgradesComparisonEuropeansteelgrades(Mildsteel,HSLA,Dual-Phase)Legend:ColdRolledHotRolledDualPhase

coldrolled

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Dimensionavailabi