SCC crack growth rate of alloy 82 in PWR primary water conditions - effect of a thermal treatment

Abstract : Stress corrosion cracking (SCC) of wrought alloy 600 and parent weld metals (alloys 182/82) is a significant cause of failure in the pressurized water reactors (PWR). Only a small number of welds fabricated from Alloy 82 is affected by PWSCC. Most of these welds were not thermally heat treated unlike the industrial practice in France. This paper describes constant load crack growth rate (CGR) tests on alloy 82 with and without post weld heat treatment. Metallurgical examination of alloy 82 was carried out using among others Electron. Backscattering Diffraction and Transmission Electron Microscopy. The heat treatment seems to be highly beneficial by decreasing the CGR. This result can be explained by the effect of thermal treatment on the precipitation in alloy 82.