Method for the evaluation of mode I fatigue crack growth rate of prestrained materials

The fatigue crack growth rate dl/dN characteristics of prestrained carbon steel were studied. In this study, the relationship between the ultimate tensile strength σB of prestrained specimens and dl/dN was the focus. Under the conditions of large-scale yielding, there is a correlation between dl/dN and σB where dl/dN versus image characteristics are modified by σB, regardless of the degree of prestrain. Under the conditions of small-scale yielding, although σB affects dl/dN, σB does not correlate strongly with dl/dN in comparison with the case under the conditions of large-scale yielding.