Effect of ECAP and Subsequent Annealing on Microstructure, Texture, and Microhardness of an AA6060 Aluminum Alloy

Abstract

AA6060 aluminum alloy was subjected to severe plastic deformation (SPD) through Equal Channel Angular Pressing (ECAP) up to 8 passes via route BC. ECAPed samples isochronally annealed for 1 hour at a temperature range of 150-450 °C. The microstructure and texture of the studied material were evaluated by Electron Backscatter Diffraction (EBSD), and the microhardness was characterized by Vickers microhardness testing. It was found that shearing texture is typically enhanced after ECAP processing. Grain size and grain growth kinetics were also studied. ECAP led to a substantial rise in hardness, with stability following 4 passes. Microstructures and material properties were relatively stable up to annealing temperatures of 150 °C. Some sub-micrometer grains were kept 2 in the 8 passes sample to annealing temperatures of 300 °C. Annealing at elevated temperature resulted in a reduction in hardness leading to a rise in grain size and a decrease in dislocation density. After annealing temperature up to 450 °C, the texture index reveals a tendency to the texture weakening and randomization. The activation energy required for the grain growth of the AA6060 alloy was exceptionally low above 300 °C.