Superplasticity and superplastic forming of Mg-Al-Zn alloy sheets fabricated by strip casting method

Superplastic properties and formability of the AZ31 sheet processed by strip casting and subsequent warm rolling were examined. Microstructure of the AZ31 sheet with thickness of 1.3 mm was uniform and composed of equiaxed grains with an average size of 6.6 mu m. The sheet exhibited excellent superplasticity with a maximum elongation of 800% at 673 K and 2 x 10(-4) s(-1). A 250 mm x 250 mm size panel with complicated embossing patterns Could be successfully formed into near net shape by gas pressure against a single female die. Small grain size and slow gain growth during deformation resulted in the superior superplastic properties at 673 K. The governing deformation mechanisms in any given strain-rate and temperature ranges could be predicted by the deformation mechanism maps for Mg-Al-Zn alloys. (C) 2007 Elsevier B.V. All rights reserved.