Environmentally assisted cracking in the fusion boundary region of a SA508-Alloy 52M dissimilar weld joint in simulated primary pressurized water reactor environments

Abstract

Environmentally assisted cracking behavior in both parallel and perpendicular directions to the fusion boundary (FB) of SA508-Alloy 52M weld joint were investigated. The grain boundaries of dilution zone adjacent to the FB are more prone to cracking than the FB. Strength mismatch and galvanic corrosion promote crack initiation along the FB or the partially mixed zone/low alloy steel interface with the loading direction vertical to the FB. In addition, the FB hinders crack growth perpendicular to the FB, most likely because severe pitting decreases the crack tip stress/strain and oxidation along the FB increases the crack growth distance.