汽车拨叉热处理工艺研究

采用正交试验法，确定的汽车拨叉零件热处理工艺参数组合，满足使用要求；分析了该工艺形成的拨叉表层碳浓度情况和碳浓度梯度分布，获得浅层碳氮共渗碳浓度梯度分布对性能的影响，采用在升温阶段手动通入适量氨气的工艺调整方法，可以缩短均温时间，保证表面硬度达到技术要求，探索了合适氨气流量确保表层不出现过量残余奥氏体和黑色组织的机理，选用MT25656分级淬火油，可以满足零件变形要求。

Explore for Heat Treatment Technics of Shifting Fork

In order to satisfy the operating requirement, orthogonal experiment is adopted to define the heat treatment process parameter combination of automobile＇s shifting fork. We grasp the effect of graded distribution of concentration of carbon on performance about shallow layer nitrocarbarizing by analyzing the status and graded distribution of concentration of carbon of shifting fork surface layer generated from the process, that is, by the process adjust method which blowing in ammonia gas as required manually in the period of heating up, the temperature uniformity time can be shortened, and the surface to the case hardness is assured to achieve technical requirement. The mechanism which the proper ammonia gas flux ensure excessive residual austenite and black organise not to appear in surface layer is researched, and it can satisfy the part distortion require ment by selecting quenching oil MT25656.