Cracking Analysis of Transition Pipe of 304 Stainless Steel

Cracking occured in the heat-affected zone of the transition pipe of 304 stainless steel during the downtime.The cracks and fracture surface were observed by optical microscopy and scanning electron microscopy(SEM).The chemical composition of base metal,welds,heat affected zone and corrosion products were analyzed.The results showed that the pipe was severely sensitized during welding.Then intergranular stress corrosion cracking was induced by the double reaction of sulfide and chloride solution and sensitization.Some protection measures are suggested.