针对一起台架试验中的柴油机主轴承盖螺栓断裂问题,对断口进行了宏观分析、微观分析、金相组织检验等,对螺栓的断裂原因进行了分析。结果表明:该螺栓失效是典型的疲劳失效,主要原因是螺栓螺纹牙底存在原始裂纹,产生疲劳断裂,通过提高螺栓搓丝质量避免类似问题的发生。 Aiming at the problem of bolt fracture of the main bearing cap of a diesel engine in a bench test, the cause of the fracture of the bolt is analyzed through macroscopical analysis, microscopic analysis and metallographic examination of the fracture. The results show that the failure of the bolt is a typical fatigue failure. The main reason is the existence of the original crack in the bottom of the bolt thread and the occurrence of fatigue fracture. The similar problems can be avoided by improving the quality of the screw rolling.