Using ball indentation to determine the mechanical properties of an Al-7475 alloy processed by high-pressure torsion

A commercial Al-7475 alloy with an initial grain size of similar to 40 mu m was processed by high-pressure torsion (HPT) for up to 2 turns at room temperature under a pressure of 6.0 GPa. The mechanical properties of the processed materials were evaluated by the ball-indentation technique to give information on the yield strength and the ultimate tensile strength. Following HPT, microhardness measurements revealed a steady increase in the hardness values from the centers of the samples towards the edges. After 2 turns, the ultimate tensile strength was similar to 1050 MPa at the edge of the disk and the measured grain size was similar to 70 nm. The results demonstrate the potential for using HPT to achieve excellent grain refinement in the Al-7475 alloy.