船舶用带铜衬套通舱管件焊接后造成表面开裂。采用化学成分分析、金相检验、断口分析和拉伸试验等方法，分析了管件开裂的原因。结果表明：带铜衬套通舱管件端面开裂类型为液态金属致脆开裂；在焊接过程中，S221锡黄铜中的低熔点金属从管件端面沿晶界进入材料内部，导致管件脆化形成裂纹，在拉应力作用下，裂纹扩展造成管件端面发生开裂。

Cracks occurred on the surface of pipe penetration piece with copper lining for ships after welding. Through chemical composition analysis, metallographic inspection, fracture analysis and tensile test, the causes of cracking of pipe fitting were analyzed. The results showed that the cracking type of end face of pipe penetration piece with copper lining was liquid metal embrittlement cracking. During the welding process, the low melting point metal in the S221 tin brass entered the material from the end face of pipe fitting along grain boundary, causing pipe fitting to become brittle and form cracks. Under the action of tensile stress, crack propagation caused the crack of the end face of pipe fitting.