通过宏观分析、金相检验、扫描电镜及X射线能谱分析、维氏硬度试验等方法, 对某电厂启动循环泵溢流管的泄露原因进行了分析。结果表明: 该溢流管失效的性质是氯离子导致的不锈钢应力腐蚀开裂; 溢流管失效是材料、应力和介质三方面问题联合作用的结果, 主要原因是氯化物在溢流管异种钢焊接接头外表面附着和富集。

The leakage reasons of the overflow tube of a starting circulating pump were studied by means of macroscopic analysis, metallographic examination, scanning electron microscope (SEM) analysis and energy dispersive spectrometer (EDS) analysis and hardness test. The results show that the failure property of the overflow tube was stress corrosion cracking caused by chloridion, and the failure was the interaction results of material quality, stress and medium. The main reason for the failure was the adhesion and enrichment of chlorides on the overflow tube dissimilar steel welding joint outer surface.