某产品在进行完寿命试验后, 分解发现胀圈断裂。通过断口分析、金相检验、硬度测试等对胀圈断裂原因进行了分析。结果表明: 胀圈发生断裂的主要原因是原材料夹杂较多, 尤其是次表层的夹杂带, 降低了材料的塑性及强度。并且寿命试验使其反复受力, 最终产生了疲劳断裂。对原材料夹杂进行严格控制, 可以避免同类事件发生。

After making life test for a product, and taking it apart, a fractured expansion ring was found. By means of fracture analysis, metallographic examination, hardness testing and so on, the fracture reason was analyzed. The results showed that the major reason for fracture of expansion ring was the raw material inclusion with more, especially the inclusion zone of subsurface reducing material’s plasticity and strength. In addition, repeated stress during the progress of life test, making the expansion ring broke finally. In order to avoid similar events, it can take strict control for the raw material inclusion.