Effect of Dissolved Oxygen Concentration and Material Factors on Stress Corrosion Cracking of Low-Alloy Steels

Abstract It is very important to clarify the stress corrosion cracking behavior of low alloy steels for the pressure boundary component materials of LWR primary coolant systems. The slow strain rate tensile test(SSRT) was carried out on three types of heavy-thick low alloy steels in high temperature water containing various levels of dissolved oxygen(DO) to investigate the effects of DO and material factors on the SCC behavior. The results obtained are as follows; 1) Susceptibility to SCC of each steel increased with DO concentration. 2) The rolled steel with higher impurity concentration had higher susceptibility to SCC at low DO concentration (100 ppb) condition. 3) The forged steel with low impurity level had superior SCC resistance even at high DO concentration(8 ppm) condition.