Short Crack Behavior on PWSCC of Mill-Annealed Alloy 600

摘要

Short crack behavior is essential in constructing a lifetime-prediction model for components of light water reactors. This study evaluates short crack behavior on primary water stress corrosion cracking (PW SCC) of mill-annealed alloy 600. Constant-load tests were conducted to investigate the short crack growth rate. Test time was fixed at 1000, 3000, 3880, and 6940 hr, and no specimen was fractured during the test. The length of each crack was measured and its Weibull probability was plotted. Crack growth rates were obtained by calculating the maximum crack length, using the Weibull parameter for each test time. Crack growth was a two-stage process, first slow and then fast. The distribution of inclination of grain boundaries which were cracked was also investigated to consider the factors that influence crack propagation. It is revealed that the crack propagation force is expressed as a function not only of stress intensity factor K but plastic strain and grain boundaries energy. A Monte Carlo simulation confirmed the above findings, showing why short crack growth occurs in two stages.