Strengthening via Ultra-Low Temperature Rolling in Strengthening 6061 Aluminum Alloy: Multi-scale Synergy and Texture Evolution

This study examines the evolution of mechanical properties and microstructure in 6061 aluminum alloy processed through room temperature rolling (RTR) and ultra-low temperature rolling (ULTR) followed by different heat treatments (annealing, solution treatment, and T6 treatment). The results demonstrate that ULTR significantly enhances the ultimate tensile strength of both annealed and T6-treated samples compared to RTR. ULTR suppresses dynamic recovery, leading to the formation of a bimodal grain structure consisting of coarse and fine grains, accompanied by an increased density of Σ3 twin boundaries and dislocations, thereby establishing a foundation for multi-scale synergistic strengthening. The ultra-low temperature environment activates deformation twinning, shifting the predominant crystallographic texture from {110} to {112}, while the increased spread in Schmid factor distribution enhances deformation direction dependence. Furthermore, ULTR introduces higher residual compressive stresses, which improve the stability of the crystalline structure. The study concludes that specimens subjected to ULTR followed by T6 treatment exhibit optimal comprehensive properties, with the strengthening mechanism attributed to the synergistic effects of grain refinement, dislocation entanglement, and deformation twinning, thereby providing a theoretical basis for the development of high-performance aluminum alloys.