某公司生产的轮胎钢圈在安装服役15 d左右后出现批量开裂现象, 采用宏观分析、化学成分分析、力学性能测试、金相检验及断口分析等方法对轮胎钢圈的开裂原因进行了分析。结果表明: 该批轮胎钢圈失效为早期疲劳开裂；轮胎钢圈轮辋侧焊缝熔合线处存在机加工刀痕, 产生缺口应力集中, 加之裂源处焊缝熔深不足降低了其疲劳性能, 加速了疲劳裂纹的萌生和扩展, 最终导致轮胎钢圈早期疲劳开裂。

Batch cracking of tyre rims of a company occured after service for about 15 days, and the cracking reason was analyzed by means of macroscopic inspection, chemical compositions analysis, mechanical properties testing, metallographic examination and fracture analysis. The results show that the failure of this batch of tyre rims was early fatigue cracking. The rim of the tyre rims presented machining marks at the fusion line, which resulted in notch stress concentration. At the same time, the inadequate weld at the crack source decreased the fatigue strength, fastened the expansion of the fatigue cracks, and eventually led to the early fatigue cracking of the tyre rims.