Causes of cracking of pipe penetration piece with copper lining for ships

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.