Experimental and numerical examination of low cycle fatigue behaviour on AISI304L steel

The integrity of the components of nuclear power plants must be guaranteed under operating and emergency conditions. It is necessary to evaluate all possible degradation mechanisms that could impact the structural integrity of nuclear power plant structures such as the pipelines and other components of the cooling systems. Environmental fatigue significantly influences the degradation mechanisms of steel components operating in water, which eventually affects the operational lifetime of the components. Exploring non-codified methods for more precise assessment of fatigue phenomena can pave the way for developing safer nuclear power plants with longer operational lifetimes. This is very important as the global demand for cleaner energy is increasing. This research study deals with a numerical investigation of the low-cycle fatigue behaviour of steel used for those nuclear reactor components where environmental fatigue plays a major role. The numerical simulation methodology is proposed to study the dependence of the kinematic hardening parameter on the strain amplitude to investigate the low-cycle fatigue behaviour of AISI 304L steel for the prediction of the fatigue curves that can be used for the estimation of nuclear power plant safety and its lifetime.

The experimental data was used to estimate the parameters required to define the material model for the numerical simulation and to validate the results of the numerical simulation of the low cycle fatigue behaviour. The presented methodology can be used for fully reversed constant-amplitude strain loading low cycle fatigue simulations for various strain ranges to predict the low-cycle fatigue behaviour of steel under repetitive loading.