某316L不锈钢管发生开裂现象,裂纹方向垂直于焊缝,采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析等方法对裂纹产生原因进行分析。结果表明:铜元素在断口表面富集,并呈沿晶分布特征;不锈钢焊管在焊接时发生了铜污染,在随后的热处理过程中,低熔点的铜液化并沿晶界渗入,使晶界脆化,在冷却拉应力的作用下产生铜污染裂纹,导致钢管开裂。

A 316L stainless steel pipe cracked, and the crack direction was perpendicular to the weld. The causes of the cracks were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis. The results show that the copper element was enriched on the fracture surface and exhibited intergranular distribution characteristics. Copper contamination occurred during the welding of stainless steel welded pipe. In the subsequent heat treatment process, low melting point copper liquefied and penetrated along the grain boundary, making the grain boundary brittle. Under the action of cooling tensile stress, copper contamination cracks were generated, resulting in cracking of the steel pipe.