Effect of Mg Content on High Strain Rate Superplasticity of Al-Mg-Sc-Zr Alloys Subjected to Equal-Channel Angular Pressing

Aluminium alloys with a chemical compositions of Al–5.8%Mg–0.52%Mn–0.2%Sc–0.07%Zr–0.16%Fe-0.1%Si and Al-5.4%Mg-0.34%Mn-0.2%Sc-0.07%Zr-0.07%Fe-0.02Si (in weight %), denoted as 1570 and 1570C, respectively, were processed by equal-channel angular pressing (ECAP) at 300°C up to strain ε~12. Extensive grain refinement provided the formation of fully recrystallized structure with the average grain sizes of 0.7 and 0.6 μm, respectively. Tensile tests were carried out in the temperature interval 200–550oC at strain rates ranging from 10-4 to 10-1 s-1. Very high tensile elongations (>1000%) were achieved in the both alloys at T350oC and strain rates higher than 10-3 s-1.