Dramatically enhanced stamping formability of Mg–3Al–1Zn alloy by weakening (0001) basal texture

Abstract

The stamping formability of Mg–3Al–1Zn (AZ31) alloy was greatly enhanced through weakening (0001) basal texture by repeated unidirectional bending (RUB). After RUB and subsequent annealing, the max (0001) texture intensity of AZ31 Mg alloy was weakened from 10.7 to 6.3 and thus the Schmid factor for basal slip system increased from 0.25 to 0.29. The RUB prepared AZ31 Mg alloy in annealed condition possessed better stamping formability than the original sheet at 373 K, e.g., larger Erichsen value (7.5 mm vs. 5.5 mm), higher and wider forming limit diagram (FLD), larger limiting drawing ratio (LDR) (1.7 vs. 1.4). The weakened (0001) basal texture resulted in a lower Lankford value (r-value) and a higher strain hardening exponent (n-value), thus enhancing the stamping formability of AZ31 Mg alloy. For the deep-drawing cup of the RUB fabricated AZ31 Mg alloy, a weakened (0001) texture and a high Schmid factor of basal slip system were still remained in the internal area, the central area and the external area of the corner in comparison to the deep-drawing cup of the original AZ31 Mg alloy.

Keywords

• AZ31 Mg alloy
• Stamping formability
• Repeated unidirectional bending (RUB)
• Microstructure
• Basal texture