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ID:36786580
大小:4.21 MB
页数:66页
时间:2019-05-15
《普通和低铬白口铸铁的变质行为和热处理制度研究》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、摘要在熔炼过程中通过加入自制的复合变质剂对熔体进行变质处理,制备了普通白口铸铁和含铬白口铸铁试样及其在相同铸造条件下的变质试样;采用金相显微组织观察、碳化物定量分析及显微硬度测量、元素面分布扫描、宏观硬度测试、冲击韧性测试及断口扫描等方法,研究了普通白口铸铁和含铬白口铸铁的变质行为;选择变质效果较好的变质低铬白口铸铁(2.6%C、1.0%Si、0.8%Mn、1.0%Cr)作为对象,对其开展了组织的加热和冷却转变研究以及各种热处理制度的研究,并从理论上进行了分析和解释。研究结果表明:(1)运用自制的复合变质剂进行变质处理,能显著改善普通白口铸铁和含铬白口铸
2、铁的组织和性能。(2)普通白口铸铁的碳含量和含铬白口铸铁的铬含量对变质效果有显著影响。普通白口铸铁碳含量为2.6%左右时,变质效果较好。含铬白口铸铁在铬含量较低时,变质效果较好;铬含量较高时,变质效果不明显。(3)变质处理能加速低铬白口铸铁碳化物在加热保温过程中溶入基体的速度,因而能降低对其进行热处理的温度和缩短热处理时间,从而降低最终热处理难度和节约热处理成本。(4)变质低铬白口铸铁获得硬度和冲击韧性综合性能较好的热处理制度为:950℃/Sh油淬一250℃/30min回火。关键词:白口铸铁;变质处理;热处理ABSTRACTNormalwhitecast
3、ironandchromiumalloyingwhitecastironwerepreparedbyusingamelt-castingprocess,andtheircorrespondingmodifiedsampleswerecastaftertheirmeltweretreatedbyacomplexmodificationtenchniqueusingself-designedcomplexmodifiers.Bymeansofmetallographicobservation,carbidequantitativeanalysisandmic
4、ro.hardnessmeasurement,elementsectiondistributionscan,macroscopichardnesstest,impacttestandfracturescanwithSEM.Themodificationbehavioursofnormalwhitecastironandchromiumalloyingwhitecastironwereinvestigated.Bvselectingamodifiedsampleoflowchromiumwhitecastiron,whichhasgoodmodificat
5、ioneffecttransformationandinfluenceofallcarriedout,theoreticalanalysisandareasfollows:astheobject,researchofheatingandcoolingkindsofheattreatmentsystemsontheobjectwereexplanationwerealsogiven,theexperimentalresults(1)Bymodifyingusingself-designedcomplexmodifiers,microstructureand
6、mechanicalpropertiesofnormalwhitecastironandchromiumaUoyingwhitecastironWasimprovedsignificantly.(2)Carboncontentofnormalwhitecastironandchromiumcontentofchromiumalloyingwhitecastironinflueneethemodificationeffectsignificantly.GoodmodificationeffectWasobtainedfornormalwhitecastir
7、onwithabout2.6%carboncontent.Chromiumalloyingwhitecastironwithlowchromiumcontentcanobtainbettermodificationeffectthanthatwithhi曲chromiumcontent.(3)Bymodifying,thedissolutionrateofcarbidesoflowchromiumwhitecastironduringthehightemperaturesoakingstagewasimprovedobviously,SOitisposs
8、ibletodecreaseheattreatmenttemperaturean
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