Aiming at the phenomenon that when AZ91E-T6 magnesium alloy is subjected to cyclic loading with strain ratio R=εmin/εmax=0and low strain amplitudes(Δε/2=0.003,0.005)，mean stress relax has a significant effect on the fatigue life, the Chaboche constitutive model was employed to describe the cyclic mean stress relaxation behavior of AZ91E-T6 magnesium alloy. The increment equation of Chaboche constitutive model was derived, and the cyclic stress-strain hysteresis curve and the mean stress of stable hysteresis loop were obtained under strain-controlled condition.The fatigue life of the material was predicted, combining the mean stress of stable hysteresis loop obtained by Chaboche constitutive model and Morrow’s equation. Numerical results and experimental values was compared. It was shown that Chaboche constitutive model can describe cyclic mean stress relaxation behavior of AZ91E-T6 magnesium alloy and combining the calculated mean stress of stable hysteresis loop and Morrow’s equation can predict the fatigue life of this material accurately.
