Experimental investigation and constitutive material modelling of low cycle fatigue of EUROFER97 for fusion applications

EUROFER97 is one of the candidate materials for structural components of fusion nuclear reactors (i.e. ITER and DEMO). Due to the plasma instabilities and cyclic operating conditions, these structural components are expected to face asymmetric thermomechanical fatigue loading. In this work, existing models based on the Chaboche viscoplasticity model have been modified in order to represent the fatigue behaviour of EUROFER97 under different strain ratios and ranges. The modified model has been parameterized based on experimental data obtained from fatigue tests of EUROFER97, in which the strain range varied from 0.6 % to 1.5 % and the strain ratio was either -1 or 0 at room temperature or 350 °C. The incorporation of the strain memory effect into the isotropic hardening due to the observed non-Masing behaviour of EUROFER97 enabled the use of unified parameters for every temperature that could cover all the different testing conditions. In order to validate the current model, the simulated results are compared to strain controlled low cycle fatigue test data performed at room temperature and 350 °C, which were not used for the parameterization. A good match between the simulation and experimental results proves the predictive capability of the proposed modified model.