Effect of a High Mg Solute Content on the Hot Workability of Al–Mg Alloys

Abstract

The workability of Al–xMg alloys with a high Mg content (Al–6Mg, Al–8Mg, Al–9Mg) was evaluated by investigating the microstructure and processing map. Hot torsion tests were conducted in the range of 350–500 °C between 0.1 and 1 s−1. Constitutive equations were derived from various effective stress–strain curves, and the thermal activation energies for deformation obtained were 171 kJ/mol at Al–6Mg, 195 kJ/mol at Al–8Mg, and 220 kJ/mol at Al–9Mg. In the case of the processing map, the instability region, which widened with increasing Mg content, was due mainly to the influence of the Mg solute, which activated grain boundary cracking and flow localization.