Failure Analysis of Stainless Steel Seamless Pipe Lap Welding

A stainless steel pipe made of 06Cr19Ni10 material from a certain company cracked during lap welding. In order to determine the cause of the steel pipe cracking, non-destructive testing, chemical analysis, metallographic examination, scanning electron microscopy, and EDS energy spectrum were used to analyze the macroscopic morphology, microstructure, fracture morphology, elemental composition, etc. of the cracked area. The test results indicate that under the combined action of welding high temperature and welding thermal stress, external zinc infiltrates into the interior of the pipe wall along the grain boundaries, weakening the austenite grain boundaries and causing embrittlement of the base material, ultimately leading to crack initiation and propagation, and the precaution measures are proposed.