Loading-direction dependence of fatigue behavior of rolled Mg alloy containing {1 0 −1 2} twins

Abstract

This study demonstrates that unlike a twin-free rolled Mg alloy, a {1 0 −1 2}-twin-containing rolled Mg alloy exhibits considerably different low-cycle fatigue characteristics depending on the loading direction on the rolling plane. In situ electron backscatter diffraction results reveal that the contribution of the initial {1 0 −1 2} twins to strain accommodation during cyclic deformation in different loading directions follows the order of rolling direction (RD) > 45° to the RD (45RD) > transverse direction (TD). This result is attributed to the angle difference between the RD-oriented twinned region and the applied loading direction. An increase in the relative twinning (or detwinning) activity causes a decrease in the mean stress. Consequently, the fatigue life of the pre-twinned alloy varies with the loading direction and follows the order of RD > 45RD > TD.