Effects of shielding gases on the microstructure and localized corrosion of tube-to-tube sheet welds of super austenitic stainless steel for seawater cooled condenser

Abstract The effects of shielding gas on the microstructure and localized corrosion of tube-to-tube sheet welds of SR-50A super austenitic stainless steel for seawater cooled condense were investigated in highly concentrated chloride environments. The localized corrosion resistance of the weld metal after welding with an Ar shielding gas supplemented with N 2 increased due to a decrease in the pitting resistance equivalent number (PREN) difference between the PREN IR of interdendritic region and the PREN DC of dendrite core. The localized corrosion was selectively initiated at the dendrite core because the PREN of the dendrite core was smaller than that of the interdendritic region.