采用宏观分析、化学成分分析、力学性能检测、金相检验、扫描电镜断口分析等方法,对42CrMo钢轴箱端盖的断裂原因进行了分析。结果表明:该轴箱端盖的断裂为多源性振动疲劳断裂,造成疲劳断裂的主要原因是在交变拉压振动的应力作用下,螺栓沉头孔内角圆周处发生应力集中,导致了多源性振动疲劳裂纹。

The fracture causes of 42CrMo steel axle box end cover were analyzed by means of macroscopic analysis, chemical composition analysis, mechanical properties test, metallographic examination and SEM fracture analysis. The results show that the fracture of the end cover of the axle box was a multi-source vibration fatigue fracture. The main reason for fatigue fracture was that under the stress of alternating tension and compression vibration, the stress concentration occured at the circumference of the inner corner of the bolt sinkhole, resulting in multi-source vibration fatigue cracks.