Effects of heat treatment and chromium content on the environmentally assisted cracking behavior of the dissimilar metal welds in simulated BWR coolant environments

The environmentally assisted cracking behavior of dissimilar metal (DM) welds, including Alloy 52 - A508 and Alloy 82 - A508, under simulated BWR coolant conditions was studied. Effects of postweld heat treatment (PWHT) on the SCC and corrosion fatigue crack growth rates of DM welds were evaluated. PWHT brought about a change of the carbide precipitate distribution and strain localization, thus leading to a redistribution of the weld residual stress. It is concluded that Cr content in the weld may not be the sole factor governing the SCC resistance; the localized strain concentration could also play an important role.