Fatigue life prediction of ferritic/martensitic steels based on universal slope equations and tensile properties obtained using small specimen

Fatigue life assessment considering neutron irradiation effects is necessary for fusion reactor. However, the fatigue life data for neutron-irradiated materials are very limited. Therefore, the prediction of the fatigue life of irradiated materials is expected. Prediction of fatigue life using the universal slope equation developed by Manson has been focused. In this work, the prediction accuracy and feasibility of utilizing small specimen for fatigue life prediction were investigated for non-irradiated reduced activation ferritic/martensitic steels (i.e. F82H-IEA, F82H-BA07 and JLF-1). The prediction accuracies for F82H-BA07 and JLF-1 were acceptably irrespective of test temperature (mostly within a factor of 2). In contrast, non-negligible errors were observed for F82H-IEA (mostly exceeding a factor of 2), which increased with the test temperature. The prediction errors for F82H-IEA might be attributed to its unexpected plastic behavior, which was not considered in the universal slope equations. The SS-J small tensile specimen showed no disadvantageous prediction accuracy regardless of the prediction equation, material, fatigue life range, or test temperature range. Therefore, the SS-J specimen could be utilized for fatigue life prediction by the universal slope equations.