Abstract The DFC and DFC2 subcommittees of the Japan Welding Engineering Society (JWES) have developed a novel approach to fatigue analysis. Parts of this analysis have been revised and incorporated into the JSME Environmental Fatigue Evaluation Method for Nuclear Power Plants, 2022 Edition (JSME S NF1-2022). The JSME code includes new best-fit fatigue curves for carbon and low-alloy steels, and austenitic stainless steels. These curves are derived from strain-controlled fatigue test data and utilize ultimate tensile strength as a parameter. Since components may generally be subjected to load-controlled mode, these best-fit fatigue curves are compared with load-controlled fatigue test data. The comparison reveals that even in the long fatigue life region, where the stress amplitude remains below the yield stress of material, the load-controlled fatigue test data deviate from the best-fit fatigue curves. To address this deviation, the best-fit fatigue curves are reconstructed using data from rotating bending fatigue tests and axial load-controlled fatigue tests. For the carbon and low-alloy steels, the best-fit fatigue curves are classified for two types of steels based on microstructure. For the austenitic stainless steels, the best-fit fatigue curves are classified based on loading mode: load-controlled and strain-controlled modes. Furthermore, the mean value and standard deviation of the best-fit fatigue curves are shown based on statistical analysis. These statistical parameters enable the calculation of design factors corresponding to target reliability levels.
Takanashi et al. (Sun,) studied this question.