AE signal characteristics of the initial Stress Corrosion Crack in the STS 304 pipe

The stress corrosion crack is one of the life-limiting mechanisms in nuclear power plant conditions. During the operation of a power plant stress corrosion cracks can initiate and grow in dissimilar metal weld pipe joints of primary loop components. In particular, stress corrosion cracking usually occurs when the following three factors exist at the same time; susceptible material, corrosive environment, and tensile stress (including residual stress). Thus, residual stress becomes very critical for stress-corrosion cracking when it is difficult to improve the material corrosivity of the components and their environment under operating conditions. Since the research conducted by Coriou et al., it is well known that Ni-based alloy and stainless steel are susceptible to stress corrosion cracking (SCC) in deaerated pure water at high temperature and the SCC is difficult to be reproduced in laboratory. In this study, stress corrosion crack was artificially produced on STS 304 pipe. And a characteristic of the AE (acoustic emission) signal, which is generated at crack initiation time, was investigated