Ratcheting and low-cycle fatigue characterizations of extruded AZ31B Mg alloy with and without corrosive environment

•The interactions between ratcheting and low-cycle fatigue of AZ31B.•Effects of mean strain, plastic strain amplitude and mean stress on fatigue life.•The interactions between ratcheting–fatigue and corrosion.•A modified energy model to predict the fatigue life. The ratcheting and low-cycle fatigue behaviors of extruded AZ31B in air and in PBS are investigated. To realize the corrosive environment and monitor the axial strain of AZ31B tested in PBS, a miniaturized chamber attachment is self-designed and an eddy current sensor is employed. Stress strain loop and strain evolution under fully symmetric and asymmetric stress cycling with and without corrosive environment are presented. The influences of twinning and detwinning, ratcheting fatigue interaction and fatigue corrosion are all discussed. Considering the effect of ratcheting and corrosion environment on damage evolution of extruded AZ31B, a modified Ellyn’s model is presented and the results agree with the experimental observations very well.