Crack growth prediction for irradiated stainless steels under the combined fatigue-creep loading

A methodology is presented in this study for estimating the crack growth of austenitic stainless steel Types 304, 304L, 316, and 316L, which are commonly used as structural materials in nuclear pressure vessels. These structural components are typically subjected to neutron irradiation and combined loadings, including repeated mechanical stresses (i.e., fatigue) resulting from startups and shutdowns, as well as creep due to on-load periods at elevated temperature. In this study, the fatigue crack length was estimated using a strip-yield based fatigue crack growth model. The model is extended to include the effects of creep deformation in a presence of hold-times, and expanded to include the effects of irradiation. Reasonable crack growth estimations are obtained for selected materials under various combined loading conditions when compared to the experimental data available in the literature.