Study on SCC Growth Resistance of Nickel-base Alloy Weld Materials with High Chromium Content in BWR Environments

Abstract

Stress corrosion cracking (SCC) growth rate of nickel (Ni) -base alloy weld materials with about 30 wt.% chromium (Cr) content has been examined in the simulated boiling water reactor (BWR) environment. The materials studied were alloy 52M and alloy 82 with enhanced Cr content of 30 wt.%. More than 20,000 hours of crack growth testing has been conducted with varying stress intensity factor (K) conditions in normal water chemistry and with changing water chemistry condition to hydrogen water chemistry. The high Cr weld materials showed significantly slow crack growth behavior under the environment, resulted in dramatically lower SCC growth rates than that of the conventional alloy 82. For the specimens after the SCC growth test, microstructural analyses have been performed on the fracture surface and cross-section near the crack tip. The results showed morphologies of oxide film and crack tip characteristics that support the superior SCC growth resistance of the materials with high Cr content in BWR environment.