TRACK: Failures/Failure Analysis
Sensitization is a known phenomenon that occurs in Alloy 600 in operating temperature ranges of 1000°F to 1800°F due to the precipitation of chromium carbides (Cr7C3 and Cr23C6). The resultant grain-boundary precipitation of these chromium carbides can result in increased susceptibility to intergranular attack when exposed to corrosive media. In this study, the effects of material characteristics (carbon content) and weld processing parameters (heat input, maximum interpass temperature) on Alloy 600’s microstructure and corrosion resistance via ASTM G28A are investigated. Additionally, mitigation techniques (lab-performed post-weld heat treatments) are explored to determine their effectiveness in reversing sensitization during weld repair efforts.