Dual frequency domain characteristics of ratcheting behavior of AZ31B alloy under asymmetrically stress-controlled loading mode

Due to the strain rate sensibility of magnesium alloys, the ratcheting behavior under a cyclic loading would be sensitive to cyclic frequency that affects the strain rate. In the present work, the ratcheting behavior under different frequencies was investigated and discussed. The result showed that the ratcheting strain and fatigue life develop with cyclic frequency in two trends. In the domain of 0.02 Hz to 0.4 Hz, the ratcheting strain decreases and the fatigue life increases with frequency. In contrast, the ratcheting strain increases and the fatigue life decreases with frequency in the domain of 0.4 Hz to 2.0 Hz. It was concluded that the fatigue life is related to the ratcheting strain, independent of cyclic hardening. The frequency effect depends on the weight of the slip and twinning deformation mechanisms, which is related to strain rate, showing the dual frequency domain characteristics.