某牵引电机吊挂焊缝失效分析

Failure Analysis of Hanging Weld of A Traction Motor

在某牵引电机检修过程中发现吊挂焊缝存在裂纹。采用外观与宏观形貌检测、扫描电镜观察,结构强度仿真分析、应力测试等技术手段对失效焊缝进行全面分析与表征,结合焊接工艺及使用环境,阐明裂纹产生的原因。结果表明:该裂纹有一定的疲劳扩展特征,属于疲劳失效。裂纹起源于电机结构应力最大位置处,手工焊接焊缝过渡不圆滑,加剧该部位的应力集中。裂纹是应力集中和运行载荷共同作用的结果。采用机器人焊接时,焊缝接头圆滑过渡,改善了应力分布和水平,有利于提高焊缝的疲劳性能。

Cracks in hanging welds were found during the maintenance of a traction motor.The failure welds were comprehensively analyzed and characterized by means of appearance and macroscopic morphology detection,scanning electron microscopy observation,structural strength simulation analysis,stress testing and other technical means.The causes of cracks were clarified by combining welding technology and operating environment.The results show that the cracks have certain fatigue propagation characteristics and belong to fatigue failure.The crack originates from the maximum stress position of the motor structure,and the manual welding seam is not smooth,which intensifies the stress concentration in this position.The crack is the result of stress concentration and operation load.When robot welding is used,the weld joint is smooth,and it improves stress distribution and level,which is beneficial to improve the fatigue performance of weld.