A Numerical Analysis on the Cyclic Behavior of 316 FR Stainless Steel and Fatigue Life Prediction

Many components in the nuclear power plant sector, such as liquid metal cooled fast breeders, are designed to function at severe temperature loading conditions, causing thermal stresses to occur simultaneously with repeated mechanical loads. As a result, low cycle fatigue is one of the most common damage mechanisms that leads to the failure of these components. Hence, in this study, the low cycle fatigue behavior of smooth cylindrical specimens made of 316 FR austenitic stainless steel, a typical material used for fatigue and creep loading applications, is investigated. The specimens have been first modeled using finite element analysis, with nominal mechanical strain amplitudes ranging from ±0.4 to ±1.2%, at 650 °C, and the numerical models have been validated against experimental hysteresis loops. The fatigue life has been then calculated, for various strain amplitudes levels, using several low cycle fatigue prediction equations, including the Coffin-Manson model, Ostergren's damage function, and Smith-Watson-Topper (SWT) damage model. The obtained results reveal that the numerically generated hysteresis loops are in good agreement with those provided in the literature. Furthermore, the fatigue lifetimes predicted using the aforementioned low cycle fatigue life models and based on the present study suggested material parameters at 650 °C, have been compared with the experimental fatigue life data available in the literature. Overall, considering the current research proposed material constants, the estimated fatigue lifetimes from the Coffin-Manson model, Ostergren damage function, and Smith-Watson-Topper equation are all in good agreement with the experimental findings and all fall within a factor of one