通过对锈蚀穿孔的天然气用不锈钢焊管进行化学成分分析、硬度检测、金相高倍检验以及焊管腐蚀形貌观察, 结合钢管的使用环境, 分析和讨论了不锈钢焊管锈蚀穿孔的性质和原因。结果表明：钢管腐蚀部位沿纵向呈点状分布于焊缝位置, 钢管的锈蚀穿孔属于点蚀; 焊缝组织中δ铁素体含量偏高是导致钢管焊缝锈蚀穿孔的内在因素, 钢管附着泥尘和接触含氯水分等腐蚀介质是导致其焊缝锈蚀穿孔的外部环境因素, 而钢管中存在的残余应力对焊缝的锈蚀穿孔具有促进作用。

The corrosive perforation properties and causes of the welded stainless steel pipes for natural gas delivery were analyzed and discussed by means of chemical composition analysis, hardness test, metallographic examination and corrosion morphology observation, considering the using environment. The results show the area of the corrosion perforation showed a punctate distribution along longitudinal direction in weld seam of the pipes. The corrosion of the steel pipes was pitting corrosion. The high δ ferrite content in the weld seam was internal factor and contacting with dust and chlorine ion in the water was the external factor that caused corrosion perforation. The presence of residual stress in the steel pipes played a promoting role in the corrosion perforation process.