汽车板簧在路试中出现早期疲劳断裂。采用化学成分分析、硬度测试、断口分析和金相检验等方法对断裂的汽车板簧进行了分析。结果表明,焊接时,飞溅的熔滴在板簧表面形成烧伤坑并形成淬火马氏体及淬火裂纹,在路试中产生应力集中而成为疲劳源,在交变应力作用下使裂纹扩展而最终断裂。

The early fatigue fracture of band springs appeared in the road testing and the fracture reasons were analyzed by means of chemical composition analysis,hardness measurement,fracture analysis and metallographic examination. The results showed that welding spatter would form a series of micropores and quenching marstensite and quenching cracks as a result of burning. Accordingly,the obtained stress concentration was the original fatigue source. Under the function of stress alternation,the micro crack expanded until fracture.