35CrMo截齿材料热处理工艺优化研究

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1、密级公开分类号TG161XI’ANTECHNOLOGICALUNIVERSITY硕士学位论文题目:35CrMo截齿材料热处理工艺优化研究作者：黑体4号徐芳芳指导教师：程巨强教授申请学位学科：材料学2018年5月5日OptimizationofHeatTreatmentTechnologyfor35CrMoPickMaterialsDiscipline:MaterialScienceStudentSignature:SupervisorSignature:AbstractTheeffectsofdifferentheattreatmen

2、ttechnologiesonthemicrostructureandpropertiesofthe35CrMocuttingpicksteelwereresearchedthroughheattreatmentoptimizationexperiments,mechanicalpropertiesandmicrostructureanalysis,andthemorphologyobservationontheimpactspecimenfractionthroughtheScanningElectronMicroscopy(SEM

3、).TheresultsshowthattheAc1andAc3phase-transitiontemperatureofthe35CrMosteelmeasuredbythehardnessmethodare750°Cand800°Crespectively.Withtheincreaseofthequenchingtemperature,thestrengthandhardnessoftheexperimentalmaterialsshowadownwardtrendafterthehigh-temperaturetemperin

4、g.Theoptimumquenchingtemperatureis800°C.Afterquenchingandhigh-temperaturetemperingforthe35CrMocuttingpicksteelbelow800°C,themicrostructureoftheexperimentalmaterialsaremainlycomposedofsorbiteandasmallamountoffinemassiveferrite,afterquenchingandhigh-temperaturetemperingbe

5、yond800°C,themicrostructureoftheexperimentalmaterialiscomposedofsorbite.Whenthequenchingtemperatureat800°Candholdingdifferenttime,thepeakoftheimpacttoughnessappearswhenholding40min,theoptimumheatingandquenchingtechnologyoftheexperimentalmaterialis800°C×40min.Whenquenchi

6、ngat800°C,thetendencyoforganizationcoarseningoftheexperimentalmaterialsindifferentholdingtimeisnotobvious.Aftertemperinginhightemperature,alltheimpactfracturesoftheexperimentalmaterialsaretoughnessfracturemorphology,andasmallamountofsulfideandoxideinclusionsexistontheim

7、pactfractures.Whenquenchingat800℃andholding40min,andtemperingindifferenttemperatures,thehardnessandthetensilestrengthoftheexperimentalmaterialsshowadecreasingtrendwiththeincreaseoftemperingtemperature.Thetemperingbrittlenessappearswhentemperingtemperaturereaches300℃.Whe

8、ntemperingat500°C,thehardnessandstrengthoftheexperimentalmaterialtendtodecreasewiththeincreaseoftheholdingtime