Comparisons of low cycle fatigue response, damage mechanism, and life prediction of MarBN steel under stress and strain-controlled modes

Abstract Low cycle fatigue response and damage mechanism of MarBN steel under symmetrical strain and stress-controlled modes is investigated at room temperature. Significant cyclic softening has been observed under both control modes, in which strain amplitude-independent and stress amplitude-dependent softening factors are presented, respectively. The tension-compression asymmetry is observed, which is the critical factor to control the cyclic fatigue resistance. The relationship between damage mechanism under both modes and microstructure is discussed. The effect of the tension-compression asymmetry on the prediction model of fatigue life is investigated based on an effective strain range-related model.