Micromechanical modeling of the cyclic softening of EUROFER 97 steel

AbstractThe quenched and tempered reduced-activation ferritic/martensitic steel EUROFER 97 is one of the candidates for structural components of fusion reactors. The cyclic behaviour of this steel during isothermal plastic strain-controlled tests is investigated at room temperature. Under Low-Cycle Fatigue (LCF) tests this steel shows, after the first few cycles, a pronounced cyclic softening accompanied by microstructural changes such as the decrease of the dislocation density inside the subgrain and the vanishing of low-angle boundaries. Based on the identified mechanisms of softening a mean-field polycrystalline model is proposed