叶轮转轴断裂分析

Fracture Analysis of Rotating Shaft of Impeller

叶轮转轴在工作中断裂,通过对故障转轴及其断口进行宏微观检查、砂轮越程槽圆角半径测量、金相组织观察、化学成分分析、力学性能测试等,对断裂原因进行分析,并对转轴相关零组件进行完整性分析。结果表明:转轴断口性质为疲劳断裂,裂纹源在砂轮越程槽底部;叶轮偏载是导致转轴发生疲劳断裂的主要原因;转轴的强度和硬度偏高,对裂纹萌生和扩展有较大的促进作用;建议转轴调质前粗车台阶或调整热处理制度,改善裂纹源处组织,提高转轴疲劳寿命。

The rotating shaft of an impeller fractured during working. Macro and micro observation, size measurement,macro and microstructure examination,chemical composition analysis, hardness and mechanical properties testing were carried out to find out the cause for the fracture. In addition, integrity analysis was conducted for the related components. The results show that the failure mode of the rotating shaft is fatigue fracture. Cracks initiated at the bottom of the grinding wheel groove. The main cause for the cracking is the unbalanced load on the impeller. The hardness and strength of the shaft is higher,promoting the initiation and propagation of the cracks. It is suggested that rough turning should be performed on the steps of the shaft before quenching or the heat treatment process should be adjusted so that the microstructure of the cracking source zone can be improved and the fatigue life can be increased.