Abstract
Based on the previous experiment on the statistical nature of the crack initiation life ti and the crack propagation life tp in stress corrosion cracking of a high strength steel in 3.5% NaCl, the distribution of the total lives tf (=ti+tp) is studied theoretically assuming that both ti and tp follow Weibull distributions. It is shown that tf follows a composite Weibull distribution approximately. This composite Weibull distribution is similar to the distribution of tp in the shorter life region, and to that of ti in the longer life region. The bent portion moves downwards on Weibull probability paper with an increase in the average ratio of ti to tp. The concepts of "initiationdominated distribution" and "propagation-dominated distribution" are proposed. Furthermore, a new interpretation of a composite Weibull distribution is presented.
