某304奥氏体不锈钢管外圈表面T型焊接加强套管的焊缝位置出现渗漏,采用宏观观察、化学成分分析、液体渗透检测、金相检验和扫描电子显微镜分析等方法研究其渗漏原因。结果表明:焊缝处存在大量气孔、未焊透、纵向裂纹等焊接缺陷,裂纹已穿透管壁;奥氏体不锈钢与加强套管为异种金属焊接,产生了较高的焊接残余应力,同时焊接热输入量过大导致不锈钢的晶界性能变弱,从而引起开裂。

Leakage occurred in the weld position of T-type welding reinforcement sleeve on the outer ring surface of a 304 austenitic stainless steel pipe. The causes were studied by means of macroscopic observation, chemical composition analysis, liquid penetration test, metallographic examination and scanning electron microscope analysis. The results show that there were a large number of welding defects such as pores, incomplete penetration and longitudinal cracks in the weld, and the cracks had penetrated the pipe wall. Austenitic stainless steel and reinforced casing were dissimilar metal welding, resulting in high welding residual stress. At the same time, excessive welding heat input led to the weakening of grain boundary properties of stainless steel, which caused cracking.