抄録
A short crack behavior is essential to construct a life time prediction model of a light water reactor component. The objective of this study is to evaluate a short crack behavior on primary water stress corrosion cracking (PWSCC) of mill annealed alloy 600. Constant load tests were conducted to investigate a short crack growth rate. Test time was fixed at 1000, 3000, 3880 and 6940 hr and no specimen was fractured during the test. Crack length was measured for all cracks and plotted to the Weibull probabilistic sheet. By calculating the maximum crack length using the Weibull parameter at each test time, crack growth rates were obtained. We found there were 2 kinds of crack growth stages. This means short cracks transform from slow speed stage to fast speed stage. Furthermore distribution of inclination of grain boundaries, which were cracked was investigated to consider the factors which influence to crack propagation. Consequently it is revealed that the crack propagation force is expressed as a function of not only stress intensity factor K but plastic strain and grain boundaries energy. Finally Monte Carlo simulation was performed to confirm the above considerations. As a result of simulation, we could clarify the reasons of existence of 2 kinds of short crack growth stages.
