Mechanical properties and microstructure evolution in an aluminum 6082 alloy processed by high-pressure torsion

A commercial aluminum 6082 alloy was used to investigate the effect of the initial condition on subsequent processing by high-pressure torsion (HPT). The alloy was prepared in two different initial conditions: (i) in a T651 annealed condition and (ii) after a solution treatment followed by over-aging and subsequent processing by equal-channel angular pressing (ECAP). All samples were processed by HPT through 1/2, 1, 2, 5, and 10 turns and then the microstructures were examined using electron backscattered diffraction (EBSD). Significant grain refinement was achieved after processing by HPT through 5 turns with measured grain sizes of ~0.5 μm in both types of alloy. Microhardness measurements were conducted to evaluate the evolution of hardness after HPT for the two initial conditions. It is demonstrated that there is a difference in the hardness values between these two initial conditions, and this difference remains almost constant after processing by HPT.