某大型动车组排障器调整板失效分析

Failure Analysis of the Motor Train Unit Obstruction Guard Adjustment Plate

通过体视显微镜分析、化学成分分析、力学性能试验、金相组织分析、扫描电镜断口分析等手段对动车排障器调整板的失效原因开展了多维度的综合分析,结果表明失效动车组S355J2W钢排障器调整板化学成分合格,室温拉伸、低温冲击性能较好,塑性较好,微观组织正常。扫描电镜断口分析结果显示,排障器调整板断裂方式为疲劳断裂,经分析应为大应力致多处起裂。调整板本身的自重较重,上臂与工作前臂的弯角处受到工作前臂的重力作用,重力下的周期性载荷作用使得弯角处产生了疲劳裂纹,而持续的重力作用下使得裂纹继续扩展直到断裂。

Through stereomicroscope analysis,chemical composition inspection,mechanical property inspection,metallographic structure analysis,scanning electron microscope fracture analysis,a multi-dimensional comprehensive analysis has been carried out on the failure causes of the adjustment plate of the motor train obstruction guard.The results show that the chemical composition of the adjustment plate of the failed motor train unit S355J2W steel obstruction guard is qualified,the room temperature tensile and low temperature impact properties are good,the plasticity is good,and the microstructure is normal.The fracture analysis results by scanning electron microscope show that the fracture mode of the obstruction guard adjustment plate is fatigue fracture,and the multiple cracks are caused by the high stress.The self-weight of the adjustment plate is heavy,and the corner of the upper arm and the working forearm is subjected to the gravity of the working forearm.The periodic load under gravity causes fatigue cracks at the corner,and the continuous gravity makes the cracks continue to expand until fracture.