The effects of grain size on the shift of neutral layer of AZ31 magnesium alloy sheets with different grain sizes ranging from 12.1 to 34.7μm were investigated by the 90° V-bending tests at 150 °C. The results show that the neutral layer tends to shift to outer region of the sheets and the coefficient of neutral layer value (k-value) increases with the increasing grain size. This phenomenon is mainly owing to the enhanced asymmetry between the outer tension region and inner compression region with the increase of grain size. Twinning dominates the deformation in inner region while slips dominate the deformation in outer region.
