On the cyclic torsion behavior of extruded AZ61A magnesium alloy tube

Twinning–Detwinning-Dominated Cyclic Deformation Behavior of a High-Strength Mg-Al-Sn-Zn Alloy during Loading Reversals: Experiment and Modeling

“…Meanwhile, as shown in Figure 7a,b, the predicting accuracy of the stress-strain behavior during the compressive unloading process is not improved. It has been shown in previous studies that back stresses induced by the twinning process make detwinning behavior easier to occur in the unloading process [40,41,44]. It is therefore inferred that the underestimation of detwinning behavior by the present model is believed to be the neglect of back stresses in the model, which can be improved to better predict the unloading behavior of Mg alloys.…”

“…It has been reported in previous in-situ neutron diffraction studies [41] that, during twinning-dominated cyclic compression, tension twins form during loading and are largely reversed during subsequent unloading, which is mainly driven by the development of back stresses [42,43], since there is no external loading during an unloading process. Therefore, the underestimation of anelastic behavior during compressive unloading is probably due to the fact that the present model does not consider the back stresses during the detwinning process, which may drive more detwinning activities during the compressive unloading process, as suggested by previous modeling and experimental studies [25,41,44]. It is noted that the present model considers a lower CRSS for detwinning relative to that of twinning, defined using the CRSS ratio, κ.…”