Abstract
The initiation process of stress-corrosion crack is composed of the initiation process of non-propagating micro cracks as the initial stage, followed by a second stage consisting of the coalescence of adjacent micro cracks formed in the first stage. Then, the self propagating third stage of cracks that can grow steadily is established after cracks larger than a certain critical size are formed as a result of the crack coalescence process. This paper discusses the distribution of the initiation time of the steady-state crack propagation expressed by an exponential distribution model, while the two random processes of the first two stages are assumed to be Poisson stochastic processes. A random-process model for the initiation of stress-corrosion cracks, and the initiation of crack propagation, based on two Poisson stochastic processes connected sequentially had been discussed, and the statistical analysis results corresponded quite well to Monte Carlo simulation results. Results of statistical analyses of crack initiation rates vs. applied stress, and of lower-bound lives vs. applied stress were shown indicating that the statistical models fit the experimental data.
