Stretch formability of AZ31 Mg alloy sheets at different testing temperatures

Stretch formability of AZ31 Mg alloy sheets was investigated by Erichsen tests at room temperature and stretch forming tests at 523 K. The as-received specimens with lower Lankford value (r-value) and higher strain hardening exponent coefficient (n-value) showed excellent stretch formability at room temperature. On the other hand, the as-received specimens with smaller grain size (higher ductility) exhibited excellent stretch formability at elevated temperature. It is suggested that reduction of strain and plastic anisotropies related to texture intensity and texture distribution should be dominant factor for excellent stretch formability at room temperature, and ductility related to fine grain size becomes important factor for stretch formability at elevated temperature, at which effects of strain and plastic anisotropies are negligibly small.