Effect of Thermal Treatment on Stress Corrosion Cracking Susceptibility in Alloy 600 and Type 316 Stainless Steel Under Simulated Pressurized Water Reactor Primary Conditions Available to Purchase

Under pressurized water reactor primary conditions, the stress corrosion cracking susceptibility of Alloy 600 (UNS N06600) is improved by chromium carbide precipitation in the grain boundaries. However, the effect of chromium depletion on stress corrosion cracking susceptibility is not completely understood. Type 316 (UNS S31600) stainless steel has minimal stress corrosion cracking susceptibility and cold work increases the stress corrosion cracking susceptibility. This study investigates stress corrosion cracking susceptibilities of Alloy 600 and Type 316 SS, which are thermally treated at a temperature of 700°C. Stress corrosion cracking did not occur in Type 316 SS regardless of the thermal treatment conditions. Alloy 600 has high stress corrosion cracking susceptibility with chromium depletion and chromium carbide precipitation. On the other hand, when chromium carbides are precipitated and chromium depletion is recovered, Alloy 600 has low stress corrosion cracking susceptibility. There are some findings that are considered to be caused by internal oxidation. The effect of chromium carbide precipitation or chromium depletion on stress corrosion cracking susceptibility is discussed through internal oxidation mechanisms.