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摘要本课题结合企业实际生产，以 GCr15和50CrMo4 为研究对象，对其表面淬火工艺和冷热加工匹配参数进行研究。通过白色共聚焦分析系统、维氏显微硬度计和 X 射线衍射仪来研究材料表面组织、表面淬硬层深度、硬度分布均匀性、残余奥氏体比例和残余应力等。经过研究发现GCr15 硬度较高、残余奥氏体含量较多，而50CrMo4淬硬层较大，淬透性较好；且随着滚珠丝杠的加工过程，材料中的残余奥氏体含量整体呈下降趋势。经过正交实验发现，冰冷处理对材料中残余奥氏体的稳定性影响很大，而时效对材料硬度和残余应力影响较大。针对不同的组织与性能指标，可得出对应的最佳工艺，对于残余奥氏体这一指标，其最佳工艺为：马氏体级别b+层深 y+文献所提供的冰冷处理+走刀速度 A+每次进刀量X+120℃ 24h 时效。49140
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毕业论文关键词 滚珠丝杠 表面淬火 正交实验 力学性能 冷热加工 微观组织
Title Effect of surface induction hardening process and technique of cold and hot working process on the microstructures and hardness distribution of high grade ball screw . Abstract In this paper, on the basis of present production in one of the enterprises, we took the steel GCr15 and 50CrMo4 used by ball screw as the research object. Effect of surface induction hardening process and technique of cold and hot working process on the microstructures and hardness distribution of high grade ball screw were studied by confocal optical microscopy, Vickers microhardness meter and X-ray diffraction. Surface microstructures of the studied steel were observed, surface induction hardening layer depth detected, hardness distribution calculated, residual austenite ratio and residual stress tested. The results were listed below. Hardness and residual austenite content in steel GCr15 was relatively higher than those in 50CrMo4, while induction hardening layer depth was larger in 50CrMo4 than in GCr15, so was the hardenability. During machining process of the ball screw, the content of retained austenite was decreased. By view of the orthogonal experiment, it is found that sub-zero treatments can affect the stability of retained austenite in the material greatly, while the influence of the aging on hardness and residual stress was larger. In order to obtain best ratio of residual austenite , a convenient technique route is, martensitic grade B + layer deep y+ cold treatment in literatures + feeding speed A + each feed amount X+ aging in 120 ℃ for 24 h.
Keywords Ball screw Surface induction hardening Orthogonal experiment Mechanical property Cold and hot processing Microstructure
目录
1引言..1
1.1目的及意义...1
1.2表面感应加热淬火工艺...1
1.3滚珠丝杠的主要失效形式...2
1.4正交实验方法...3
2实验方法和内容..4
2.1实验样品...4
2.1.1表面淬火实验样品4
2.1.2冷热加工正交实验样品5
2.2实验内容和实验原理...6
2.2.1X射线衍射仪测量残余奥氏体6
2.2.2X射线衍射仪测量残余应力8
2.3实验样品制备及实验参数...8
2.3.1X射线衍射仪测量残余奥氏体8
2.3.2X射线衍射仪测量残余应力..10
2.3.3白色共聚焦分析系统..11
2.3.4维氏显微硬度计..11
3表面淬火工艺实验结果与分析12
3.1白色共聚焦分析系统结果与分析.12
3.2硬度测量结果与分析.13
3.2.1加工过程对材料均匀性的影响..17
3.3残余奥氏体测量结果与分析.19