316L奥氏体不锈钢碱液储罐开裂原因

Cracking causes of 316L austenitic stainless steel caustic storage tank

某核电站316L奥氏体不锈钢碱液储罐发生了泄漏,采用宏观观察、化学成分分析、金相检验、硬度测试及残余应力分析等方法对该储罐开裂原因进行了分析。结果表明:储罐内壁焊缝两侧出现与焊缝平行的环向裂纹和垂直的轴向裂纹,前者主要受焊接残余拉应力作用,后者主要受冷加工残余拉应力作用,两类裂纹均为碱致应力腐蚀开裂。

The leakage of 316 L austenitic stainless steel caustic storage tank occurred in a nuclear power plant.The cracking causes of the tank were analyzed by macroscopic observation,chemical composition analysis,metallographic testing,hardness testing and residual stress analysis.The results show that the annular cracks parallel to the welding seam and the axial cracks perpendicular to the welding seam were found on the inner wall of the storage tank.The annular cracks were mainly affected by the welding residual tensile stress,while the axial cracks were mainly affected by the cold worked residual tensile stress.These two kinds of cracks were both caustic induced stress corrosion crack.