客车后桥壳半轴套管失效分析

Failure Analysis of Half-axle Tube of Bus Rear Axle Casing

某客车后桥壳半轴套管在使用过程中出现裂纹,对其进行了宏、微观检验、力学性能测试和化学成分分析以查明失效原因。检验结果表明,半轴套管的裂纹属于表面淬火裂纹。裂纹位于半轴套管内轴承挡肩R圆角表面,热处理工艺控制不当使该处产生很大的残余拉应力超过了材料的断裂强度是裂纹产生的主要原因。

The cracks were found in half-a^e tube of a bus rear axle casing during operation. The crack causes were checked out by the means of macrographic examination, micro-examination, mechanics performance testing and chemical component analysis. The test results show that the cracks are surface quenching cracks. The crack location is on the surface of inner bearing retaining shoulder fillet. The incorrect heat treatment process results in tension residual stress exceeding break strength of the material, and it is the main cause of the crack formation.