低ひずみ速度試験中に発生・進展する応力腐食割れの直接観察およびその破壊力学的統計的評価

抄録

Slow strain rate test, SSRT, has been widely used for studies of stress corrosion cracking, SCC. In evaluating SCC susceptibility, it is important to analyze initiation and growth of SCC separately even if SSRT is used. Then we have developed a new SSRT system with a high magnification and high focusing depth CCD camera in order to make in-situ observation of crack behavior on the whole specimen surface during SSRT, and analyzed initiation and growth of crack separately by using fracture mechanics and statistics. As a result, the number of pits, at which crack generated, was found to increase with increase in strain. The Weibull distribution was found for K_ISCC and its mode was 2MN·m-^3×2. While, crack growth rate showed double exponential distribution and its mode was about 10^-8m·s^-1. Thus, This technique could evaluate SCC susceptibility by separating crack initiation and growth.