Twinning character and texture origination in the randomly-oriented AZ31B magnesium alloy during cold-rolling

Abstract

Based on generalized Schmid factor (G-SF) calculation, the twinning character and texture development in the rolling plate of randomly-oriented AZ31B magnesium alloy were investigated in this work. The results showed that when the rolling reduction/nip angle is low, the twin type selection is independent of crystal orientation or G-SF due to the significant difference of critical resolved shear stress (CRSS) between extension twinning and contraction twinning. The twin variant selection does not intimately follow the Schmid criterion. In comparison, the extension twin variant selection departs more from the G-SF prediction than the contraction twin variant selection. The orientations of the matrix grains develop gradually tending to distribute around the normal direction (ND), which promote the activation of contraction twinning. The basal texture results only from the orientation development of the matrix grains, depending on the basal slip and the pyramidal slip, which was explained in terms of a crystal rotation by the dislocation interactions.

Keywords

• Randomly-oriented magnesium alloy
• Generalized Schmid factor
• Twin type selection
• Twin variant selection
• Texture formation