汽车弹簧断裂分析

汽车用弹簧(后簧)在试验过程中发生断裂。对断裂弹簧进行外观检查、金相组织和显微硬度检测,对弹簧断口进行宏微观检查、能谱分析,综合分析弹簧的断裂性质和原因。结果表明,弹簧的断裂性质为疲劳断裂。断裂过程及原因为:弹簧喷丸之前,由于磁粉探伤机故障产生电火花放电,引起弹簧局部接触高温而在表面形成一个烧伤区;该烧伤区破坏了弹簧的表面完整性,导致弹簧疲劳寿命大幅度降低,在试验载荷作用下,从烧伤区萌生疲劳裂纹并发生断裂。改进措施为加强关键设备、工艺的监控,以避免弹簧生产过程中受到异常损伤。

Failure Analysis of Automobile Spring

The spring(rear spring) of an automobile fractured during testing. The fail mode and cause were analyzed by appearance observation, metallographic examination and testing hardness of the spring, as well as macro-and micro-observation of the fracture surface and energy spectrum analysis (EDS). The results show that the failure mechanism of the spring was fatigue, which was caused by the burned zone induced by local high temperature contact because of spark discharge of the failure of the magnetic powder inspection machine before the shot-blasting process. The burned zone damaged surface integrity of the spring, and greatly decreased fatigue life of the spring. Under the effect of test load, fatigue crack initiated from the burned zone and the spring fractured early. Improvement measures were proposed: the main equipment and process should be supervised in order to avoid abnormal damage during production process of the spring.