摘要
航空发动机轴承用Ｍ５０ＮｉＬ钢高温（９００～９２０℃）碳氮共渗，可获得均匀细小的淬火、回火组织，其疲劳裂纹扩展抗力和高温硬度显著高于Ｍ５０钢。分析认为，疲劳裂纹沿渗层的扩展行为与残余奥氏体的诱发裂纹闭合效应，残余压应力，以及渗层塑性、韧性对断裂机制的影响有关；渗层高温硬度的提高则是马氏体回火相析出发生改变的结果。
The case microstructure of the carbonitriged M50NiL steel are apparently refined.The hot hardness and the fatigue crack resistance of the carbonitrided case are apparently higher than M50 steel.The characteristics of the curves of da/dn are attributed to the combined influence of induced crack closure of the retained arstenite,the residual compressive stress,the ductility and toughness of the case and the fracture mechanism.It is attributed to precipitation during tempering of martensite,in which the hot hardness is increased.
