Mechanical properties and thermal stability of AA5052 processed by high-pressure torsion

Abstract

High-pressure torsion (HPT) is a technique for increasing material strength through grain refining and dislocation strengthening. The goal of this research is to investigate at the material's stability after HPT processing and high-temperature exposure. Prior to HPT processing, the 10 mm diameter AA5052 sample was solution treated at 550 °C for 5 h. The sample was then processed by HPT at 6 GPa and torsional force of 1.0 rpm for 5 turns at room temperature. Following that, the sample was annealed for 1 h at 200 °C. When compared to the solution-treated state, the Vickers microhardness and tensile strength after 5 turns reveal a 135% and 199% improvement in hardness and strength, respectively. Due to the annihilation mechanism, the hardness and tensile strength of the material reduced by up to 25% and 27% respectively after exposure at 200 °C. The result shows a tremendous improvement in the mechanical properties after HPT processing as well as adequate stability at 200 °C. The TEM analysis revealed that HPT processing resulted in grain size refinement and high-angle grain boundaries which contribute to the excellent mechanical properties.