Using ring samples to evaluate the processing characteristics in high-pressure torsion

An Al–3% Mg–0.2% Sc alloy was processed by high-pressure torsion (HPT) using samples in the form of solid disks and rings. Following HPT, all values of the measured Vickers microhardness fall onto a single curve when plotted against the equivalent strain, such that there are increasing values of hardness at the lower strains and hardness saturation above equivalent strains of ∼40. This saturation level is independent of the number of revolutions and the applied pressure. The grain size following HPT is ∼220 nm, and tensile tests show that the material is superplastic at a testing temperature of 573 K.