北京科技大学材料力学实验报告(国际班).docx

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1、TensileTestofLowCarbonSteelatRoomTemperature1.Experimentalobjective(1)Measuretheintensityandplasticperformanceoflowcarbonsteelwithdifferentheattreatmentconditionthroughthetensiletest.(2)Accordingtostress-straincurve,determinethestrainhardeningexponentandcoefficientduringplasticdeformation.Make

2、suretheexperimentproceedaccordingtostandardrequirement.2.Principleofexperiment(1)Tensiletestisausualmethodtomeasuremetalmaterialperformance,whichcanmeasureintensityandplasticperformance.(2)Thetensilecurvemeasuredbytensiletestisalsoagoodmethodtoobservetheprocedureofmetalplasticdeformation.Durin

3、gtheunevenplasticdeformation,Hollomanformulacannicelydescribetheruleofplasticdeformation.Inthisempiricalformula,strainhardeningexponentkandstrainhardeningcoefficientnreflectthematerialproperties.(3)Lowcarbonsteelisakindofmetalwithgoodplasticity.Dealtwithdifferentheattreatment,steelacquiresdiff

4、erentmicrostructure,whichcausesdifferentstrengthandplasticity.Observethechangeoflowcarbonsteel’spropertyandchangeofn,kwithdifferentheattreatmentastoquenching,annealingandnormalizing.3.EquipmentandinstrumentsVerniercaliper，maximumaccuracyis0.02mmlininginstrument,accuracyis±1%Extensometer,gaugei

5、s50mmUniversalmaterialtestingmachineWDW-200D4.Procedure(1)Linemeasurement:usingVerniercalipertomeasurethediameterofspecimenandthenlinethespecimenwithlininginstrument.(2)Installthespecimen:settheextensometerbetweenthegages,thenclampthespecimenbetweenthechuck.Theextensometerisusedtomeasurethedef

6、ormationofspecimen.(3)Operationofinterface:setthedataoftensiletestwiththereminderofcomputer.Resettheextensometerthenpressthe“start”bottom.Thecurveofloadanddisplacementofthelowcrossbeamwillshowonthecomputer.Whenthecurvebecomesevenandloadapproachestohighestvalues,weneedtoremovetheextensometertop

7、reventitbeingdamaged.(4)Continuethetest,observetheneckingphenomenonandthenthespecimenbreakdownwiththecomputerstopthetest.Takeoffthespecimenandobserveitsfracturesection.(5)Measurethebrokenspecimen:usingVerniercalipertomeasurethegagelengt