【作者】 王毅；

【导师】 樊景云； 徐克权；

【作者基本信息】 哈尔滨理工大学 ， 材料工程， 2005， 硕士

【摘要】 本文研究了20CrMoH 汽车齿轮用渗碳钢的预先热处理等温正火工艺对组织和性能的影响,还研究了不同渗碳热处理工艺参数对渗碳层显微组织的影响。通过拉伸、冲击和台架试验等性能分析试验,最终确定了20CrMoH 齿轮钢热处理渗碳淬火最佳工艺参数。20CrMoH 汽车齿轮用渗碳钢采用普通正火,由于钢件内外冷却速度不一样且连续冷却转变是在相当大的过冷范围内完成的,因而所获得的显微组织和硬度难以达到技术标准要求;采用等温正火可以获得良好的显微组织和硬度,以利于切削加工性能。同时有效减小热处理淬火变形。研究了20CrMoH 汽车齿轮用钢在连续渗碳生产线不同区域渗碳过程的碳势、渗碳温度、淬火温度等工艺参数对有效硬化层、显微组织、表面硬度、心部硬度以及碳浓度分布和渗碳层硬度分布的影响规律。确定了最佳的热处理渗碳工艺参数为:Ⅰ区880℃;Ⅱ区900℃、碳势为1.00 %;Ⅲ区920℃、碳势为1.15%;Ⅳ区900℃、碳势为0.90 %;Ⅴ区835℃、碳势为0.90%;回火温度190℃,推料周期为25 分钟。对按此最佳热处理工艺参数生产的20CrMoH 齿轮装配CA7-100 变速箱总成后进行了台架寿命试验,验证了此最佳工艺的可行性。此工艺应用于汽车生产中取得了极为可观的经济效益。更多还原

【Abstract】 In the present study, the effect of pre-heat treatment of isothermal normalizing on the structure and performance of 20CrMoH gear steel were studied, and the effects of the parameters of different carburizing on the microstructure in carburized layers of the steel were also investigated. According to the results of tension, impact and bench tests, the optimal carburizing-quenching parameters of the 20CrMoH gear steel were determined. For using the normal normalizing, because the continues cooling transformation takes place within a wide range of temperature and also because of the different cooling rate in different parts of the steel pieces, it is difficult for the obtained microstructure and hardness to fit for the engineering standard. However, when using isothermal normalizing, the optimal microstructure and hardness can be obtained, which also reduces quenching deformation. The effect of processing parameters such as carbon potential, carbonizing temperature, quenching temperature on the rules of effective harden layer, microstructure, interior rigidity, distribution of hardness and carbon concentration were studied. Based on the above analysis, the optimal parameters of carburizing processing are determined as follows: the temperature in the zones of I, II, III, IV, and V is 880℃, 900℃, 920℃, 900℃and 835℃, respectively. The carbon potential in zones of II, III, IV and V is 1.00%, 1.15%, 0.90% and 0.90%, respectively. The temping temperature is 190 ℃, and the cycle of feed is 25min. The bench tests was carried out in the CA7-100 gearbox assembled with 20CrMoH gear steel treated at the optimization condition parameters, which proofs the technique proposed in the study to be excellent. The optimization technique has been adopted in automotive truck, and a great benefit is gained.更多还原