试验件裂纹失效分析

Failure Analysis of Cracks on the Test Pieces

通过对试验件进行外观检查、断口宏观及微观检查、高倍检查、化学成分光谱分析及硬度测试等工作，确定试验件的裂纹性质及产生原因。结果表明：试验件裂纹性质为双向多源疲劳开裂，裂纹源位于接管嘴根部R角处，为零件结构应力集中部位。试验件在进行循环收放试验过程中承受交变振动载荷，促使裂纹在此处萌生及扩展。

In order to characterize cracks and find out the causes of leaks, macroscopic inspection, scanning e- lectron microscopic inspection, chemical analysis, microstructure observation and micro-hardness test were per- formed. As a result, the crack on the test pieces was a biaxial fatigue crack. It originated from the root fillet of the connecting nozzle, which was the spot of stress concentration. Since an alternating liberation load was in- duced on the test pieces during the operating test, fatigue crack originated and expanded accordingly.