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1、密級公開分類號TG161XI’ANTECHNOLOGICALUNIVERSITY碩士學(xué)位論文題目:35CrMo截齒材料熱處理工藝優(yōu)化研究作者:黑體4號徐芳芳指導(dǎo)教師:程巨強(qiáng)教授申請學(xué)位學(xué)科:材料學(xué)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