球墨铸铁等温处理的相变及机理研究(上贝氏体)

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1、本科毕业论文题目：球墨铸铁等温处理的相变及机理研究(上贝氏体)院（部）：材料科学与工程学院专业：金属材料工程班级：姓名：学号：指导教师：完成日期：2007年6月24日毕业论文目录摘要·································································IIABSTRACT···························································III1前言1.1选题背景·····················

2、·········································11.2贝氏体球墨铸铁现状····················································11.3本文研究的目的························································42球墨铸铁等温处理相变机理2.1贝氏体转变机理························································62.2贝氏

3、体类型····························································72.3球墨铸铁等温处理·····················································8-36-毕业论文3实验方案的制定3.1实验方案的论证························································93.2实验方案的制定·····································

4、···················93.3结论·································································154实验过程及相变分析4.1实验设备·····························································164.2实验步骤·····························································174.3实验数据分析········

5、················································174.4实验结论····························································325结论································································33谢辞-36-毕业论文·····························································

6、····34参考文献·······························································35摘要本论文研究的目的是在控制水冷-等温的条件下，获得均匀的上贝氏体+奥氏体的球墨铸铁。观察在不同条件下得到的显微组织形态，分析组织形成的原因及转化机理。实验研究发现：Φ22mm试样采用40℃的水冷却，停留3-5秒、60℃的水停留3-7秒、80℃水停留5-11秒，均能得到均匀上贝氏体+奥氏体组织。根据IT曲线分析：随着淬火时间的增长，可以依次获得屈氏体、屈氏体+上贝氏

7、体+残余奥氏体、上贝氏体+残余奥氏体、上贝氏体+下贝氏体+残余奥氏体、上贝氏体+下贝氏体+马氏体+残余奥氏体。硬度逐渐升高。观察发现，冷却时间短时，碳的扩散能力较强，形成的铁素体板条较宽，而且条间距离也较大；随着冷却时间的延长，碳的扩散能力下降，形成了羽毛状的上贝氏体，由于硅元素的存在，抑制了碳化物的析出，贝氏体之间以奥氏体为主。关键词：水冷-等温；上贝氏体；冷却时间；硅-36-毕业论文PhaseTransformationandMechanismStudyofIsothermalTreatmentfortheD

8、uctileCastIron(UpperBininte)ABSTRACTThepurposeofthisresearchpaperisundertheconditionofwatercooling––isothermaltoachieveuniformductilecastironofupperbaininteandaustenite,andoverpassobservi