12Cr2Ni4A弹性安装座裂纹原因分析

Cause Analysis on Cracks in 12Cr4Ni2A Elastic Mounting Case

通过对12Cr2Ni4A弹性支座进行裂纹宏微观形貌观察、断口及能谱分析、残余应力测试,研究了12Cr2Ni4A故障件裂纹的性质及产生原因。结果表明:裂纹性质为磨削应力裂纹,产生于磷化处理之前,试车过程中未发生扩展;裂纹区域氰化采用整体镀铜保护,氰化和非氰化边界压应力分布复杂,后续倒角及抛光工序使得该区域压应力降低或产生拉应力。工艺路线缺少酸蚀检查和消除应力措施,最终导致产生裂纹.

The properties and causes of the crack of 12Cr2Ni4A elastic mounting case were studied by observing the maro and micro morphology of the faulty part. The properties and cause of the crack of the failure part of 12Cr2Ni4A was analyzed. The results show that the character of the crack is grinding stress crack, which occurs before phosphating treatment and does not propagate during engine testing. The cyanidation in the crack area is protected by integral copper plating, which makes complex compressive stress distribute at the cyanidation and non-cyanidation boundary. The subsequent chamfering and polishing processes reduce the compressive stress or generate tensile stress in the area. The process route lacks acid corrosion inspection and stress elimination measures, which eventally leads to cracks.