Overview of fatigue crack initiation in carbon and low-alloy steels in light water reactor environments

Recent test data illustrate potentially significant effects of light water reactor (LWR) coolant environments on the fatigue resistance of carbon and low-alloy steels. The crack initiation and crack growth characteristics of carbon and low-alloy steels in LWR environments are presented Decreases in fatigue lives of these steels in high-dissolved-oxygen water are caused pri marily by the effect of environment on growth of short cracks <100 mu m in depth. The material and loading parameters that influence fatigue life in L WR environments are defined. Statistical models have been developed to esti mate the fatigue lives of these steels in LWR environments, and design fati gue curves have been developed for carbon and low-alloy steel components in LWR environments. The significance of environmental effect on the current Code design curve is evaluated.