**4. Conclusions**

The effect of secondary deformation mechanisms (prismatic <a> slip, pyramidal <c+a> slip, and -1011 contraction twinning) on the plastic deformation of AZ31 magnesium alloy during in-plane compression (IPC) along the rolling direction (RD) and in-plane tension (IPT) along the transverse direction (TD) had been numerically investigated by VPSC modeling with different combinations of deformation mechanisms. The following conclusions can be drawn.

(1) As for the pyramidal <c+a> slip, it is the first candidate for sustaining the extra plastic strain during the plastic deformation. The increment in the activity of the pyramidal <c+a> slip contributes to the increase of flow stress in mechanical response during IPC along RD and IPT along TD. Moreover, during IPT along TD, its grea<sup>t</sup> growth contributes to the splitting of pole densities around ND in the {0002} pole figure.

(2) The increment in the activity of prismatic <a> slip is also conducive to the improvement of flow stress in mechanical response during IPT along TD. In addition, during IPC along RD, its grea<sup>t</sup> growth contributes to the splitting of pole densities around RD in the {0002} pole figure.

(3) The -1011 contraction twinning has a minor influence on the plastic deformation of AZ31 magnesium alloy during IPC along RD and IPT along TD as well as the corresponding mechanical responses. However, during IPC along RD, its grea<sup>t</sup> growth contributes to the appearance of pole densities close to ND. Consequently, it is better to include the -1011 contraction twinning in VPSC modeling to predict the texture more accurately during the plastic deformation of AZ31 magnesium alloy.

**Author Contributions:** Conceptualization, methodology, visualization, and writing—original draft preparation, Y.L.; software, validation, and writing—review and editing, L.H.; formal analysis and data curation, T.Z. and M.Y.; and supervision, J.Z.

**Funding:** This research was funded by the National Key Research and Development Program of China (grant No. 2016YFB0301105).

**Conflicts of Interest:** The authors declare no conflict of interest.
