旋翼轴螺栓螺纹尾牙裂纹原因分析

Cause analysis on crack of rotor shaft bolt thread tooth

35Cr2Ni4MoA旋翼轴螺栓经磁粉探伤发现在螺纹端尾牙1~2牙处存在纵向微裂纹。通过对微裂纹宏微观形貌观察和螺栓显微组织及硬度的检测,同时结合螺栓生产工艺对微裂纹形成原因进行分析。结果表明,由于磨削冷却不当,导致螺纹端尾牙1~2牙处产生二次淬火,出现细针状马氏体组织,造成磨削烧伤,在二次淬火应力作用下产生淬火裂纹。通过加强磨削冷却检测和相关人员培训,完善设备维护制度,避免此类问题再次产生。

Longitudinal cracks were found on the 1-2 teeth of the tail end of the 35Cr2Ni4MoA rotor shaft bolt thread through magnetic particle testing.Combining with the bolt production process,the causes of microcrack formation were analyzed by means of macro and micro morphology observation of the microcracks and microstructure and hardness examination of the bolt.The results show that due to improper cooling during grinding,secondary quenching occurred at the 1-2 teeth of the thread end tail tooth,resulting in fine needle-like martensite appears,causing grinding burns and quenching cracks under secondary quenching stress.In order to avoid such problems recurrence,it is recommended reinforcing the grinding cooling detection and related personnel training and improving the equipment maintenance system.