Analysis and repair of welding crack in 304 stainless steel flange

The cracks in 304 stainless steel welds and base metal were analyzed during the overhaul, it was found that welding slag in the weld and lack of penetration were the reasons of cracking of welded joint. Metallographic analysis of base metal showed that carbides precipitate in grain boundary of 304 stainless steel, which likely results in the intergranular corrosion that could cause the cracking of base metal. During the welding process, the multi-pass welding easily caused the intergranular corrosion of heat affected zone, which can lead to cracking. During the cooling process after manufacturing of 304 stainless steel forging flange, it should be avoided remaining at sensitization temperature for too long time, and fast cooling after solution should be taken to avoid intergranular corrosion. The welded joint of 304 stainless steel was qualified by welding inspection after repairing by strictly controlling interpass temperature and low heat input during and fast welding.