某厂硫磺装置经过短暂的开、停工后,材质为304不锈钢的管线大小头发生开裂.通过金相显微镜和扫描电镜对失效件裂纹及断口形貌进行表征,并通过电子能谱对母材、焊缝、热影响区、腐蚀产物的化学成分进行了分析.结果表明,管线的泄漏是由于在焊接时受到敏化处理,并在氯化物、硫化物溶液的双重作用下迅速发生沿晶应力腐蚀开裂所致.提出了相应的防护措施.

Cracking occured in the heat-affected zone of the transition pipe of 304 stainless steel during the downtime.The cracks and fracture surface were observed by optical microscopy and scanning electron microscopy(SEM).The chemical composition of base metal,welds,heat affected zone and corrosion products were analyzed.The results showed that the pipe was severely sensitized during welding.Then intergranular stress corrosion cracking was induced by the double reaction of sulfide and chloride solution and sensitization.Some protection measures are suggested.