某高速动车组在行驶12×10⁵ km后进行检修时发现组内多件牵引电机非传动端盖在与传感器壳体的配合面处出现裂纹，通过宏观观察、X射线检测、残余应力测试、断口宏微观分析、能谱分析、金相检验、化学成分分析、拉伸试验等方法，对端盖开裂原因进行了分析。结果表明：端盖裂纹为固溶热处理工序时发生过烧，在后期加工应力的作用下引起的沿晶开裂。最后提出了相应的工艺改进建议。

When high-speed electric multiple units were overhauled after driving for 12×10⁵ km, it was found that cracks appeared in the joint of the non-transmission end caps and the shell of the sensor. The causes of cracking were analyzed by means of macroscopic observation, X-ray examination, residual stress test, fracture macro and micro analysis, energy spectrum analysis, metallographic examination, chemical composition analysis, tensile test and so on. The results show that the end caps were overheated during the solid solution heat treatment process, and the intergranular cracking was caused by the later processing stress. Finally, some suggestions on process improvement were put forward.