The Effect of Severe Plastic Deformation on Mechanical Properties for A6061 Aluminum Alloy Fabricated by Multitypes of Bending Forming

Severe plastic deformation (SPD) is a well‐known processing technique used to impose large plastic strains and modify the mechanical properties of metal‐based materials. In this work, SPD was introduced into A6061 aluminum alloy sheets via two forming processes: differential diameter rolling (DDR) and V‐bending. This hybrid DDR V‐bending approach addresses the limited understanding of how shear‐dominated prestraining produced by asymmetric rolling affects the subsequent bending response, spring‐back behavior, and energy absorption of A6061 aluminum alloy sheets, which are not fully captured by conventional symmetric rolling. The DDR process was performed at a rolling speed ratio of 1.15 using four sample reorientation conditions between successive passes, denoted as ND‐, RD‐, TD‐, and UD‐based routes. The thickness reduction ratios were 20%, 30%, and 40%, performed through three passes of the DDR process. Following the DDR process, the sheets were bent via a 90° V‐die to assess the following mechanical properties: hardness, maximum bending load, bending deflection, bending energy absorption, and spring‐back. Results of the experiments indicated that the thickness reduction ratio had a positive influence on strain hardening, leading to an increase in both hardness and spring‐back. However, the maximum bending load decreased with an increase in thickness reduction ratio, which occurs due to the reduction in the sheet thickness following the DDR process. Furthermore, the spring‐back angle and spring‐back factors were found to be higher for samples processed via the ND and RD rolling routes. The sheets rolled along the ND route produced the highest improvement in mechanical properties. Bending energy absorption increased with an increase in the thickness reduction ratio. The results of this study demonstrate that the DDR‐V‐bending process is effective in the modification of mechanical properties of A6061 aluminum alloy sheets. However, the reduction in bending load indicates a potential negative impact of the DDR process on the formability of the sheets.