The effect of weld chemistry on the likely primary water stress corrosion cracking susceptibility of Alloy 82 dissimilar metal welds

Alloy 82 dissimilar weld joints between carbon steel and Alloy 600 were exposed to a simulated primary water environment consisting of hydrogenated steam at 480 °C and 1 bar. Dilution from the carbon steel to the weld was significant, particularly in the root where Fe was enriched to 35 at. % and Cr was depleted to 10 at. %. The heterogeneous composition of the weld from root to crown resulted in differences in internal and external oxidation tendency. An Fe-rich external surface oxide formed on the weld root which may help to prevent embrittlement and SCC by internal intergranular oxidation.