Low cycle fatigue behavior of extruded AZ31B magnesium alloy

The strain-controlled fatigue behavior of an extruded AZ31B magnesium alloy was investigated under symmetric loading at different total strain amplitudes. It is found that except for the low strain magnitude of 0.5%, the alloy exhibits obviously cyclic strain-hardening characteristics during fatigue at strain magnitudes of 0.7%, 0.9%, 1.3% and 1.5%. At the strain of magnitude 0.5%, the alloy exhibits a cyclic hardening characteristic in the initial stage and then a stress constant remaining in the late stage. The hysteresis loop is symmetrical in shape at the strain magnitude of 0.5%, and becomes asymmetrical due to the twinning-detwinning process when the strain magnitude increases. The shape difference of the hysteresis loops between the low and high strain magnitudes was discussed in terms of the differential deformation mechanisms.