Effect of Short-Time Heating after ECAP Processing on Mechanical Properties of 6061 Aluminum Alloy

This study aimed to enhance the strength and ductility of Al-Mg-Si alloys through the combination of severe plastic deformation and heat treatment. A 6061 aluminum alloy, subjected to equal-channel angular pressing (ECAP) following solution treatment, was heated from 100°C to 400°C for 10 seconds. Electron backscatter diffraction analysis revealed that the fine grains produced via ECAP processing remained intact after a brief heating duration of 10 seconds at 400°C. Hardness test results indicated that the alloy begins to recover after short-term heating at approximately 200°C, with the strengthening phase precipitating at around 250°C. In contrast, artificial aging without short-term heating post-ECAP processing resulted in decreased alloy strength, likely due to recovery effects (reduction in dislocation density) during artificial aging. The 0.2% proof stress and ultimate tensile strength of specimens heated briefly at 200°C post-ECAP processing increased by 18 and 15 MPa, respectively, due to subsequent artificial aging. It is hypothesized that hardening from precipitation strengthening was induced by artificial aging, while dislocation density reduction was attributed to short-term heating. Specimens heated briefly at 300°C post-ECAP exhibited a significant decrease in strength after artificial aging. Although recovery occurred post-ECAP processing followed by short-term heating, the simultaneous precipitation state contributed to the alloy’s strength and ductility during subsequent artificial aging.