Effect of heat treatment on grain boundary carbides and primary water stress corrosion cracking resistance of Alloy 182 weld

Abstract

Alloy 182 welds were heat-treated at 600, 620, and 650 degrees C for 10 h. The primary water stress corrosion cracking initiation test showed significant improvement in the cracking resistance of the heat-treated specimens over the as-welded specimens. Microstructure analysis demonstrated that Cr23C6 grain boundary carbides dominated in the as-welded specimen, while Cr7C3 carbides were dominant after heat treatment. The depth of grain boundary oxidation ahead of the crack tip was large for the as-welded specimen, but less for the heat-treated specimens. Therefore, the presence of Cr7C3 carbides, in part, contributed to the improved cracking resistance of the Alloy 182 weld.