Multi-mode recrystallization behavior of ribbon-like grains in solution heat treatment of cold-deformed aluminum alloy

Refinement of ribbon-like grains during solution heat treatment (SHT) is critical for the service performance of high-strength aluminum alloy components formed by cold forming. However, heterogeneous deformation during forming often leads to non-uniform microstructures. In this work, compression, radial compression with in-plane shear and axial compression with through-thickness shear were applied to an extruded 2A12 aluminum alloy tube to generate diverse deformation modes under different loading directions and their effects on recrystallization were systematically investigated. Microstructure evolution during SHT was characterized by electron backscatter diffraction (EBSD). The results show that recrystallized grain morphology and size are highly sensitive to deformation modes and loading directions. Compression along the long or short axis of the ribbon-like microstructure leads to distinct recrystallization behaviors. Small axial compression preserves ribbon continuity and promotes orientation-gradient boundary transition zones, which act as preferential nucleation sites during SHT, resulting in abnormal recrystallization with coarse grains. In contrast, large deformation fragments the ribbon structure, generating highly distortion regions that promote extensive nucleation and conventional recrystallization. Radial compression induces stronger thinning and fragmentation, while recovery-induced serrated boundaries provide uniformly distributed nucleation sites, leading to fine equiaxed grains. Through-thickness shear and compression exhibit recrystallization behavior similar to that under large axial compression. After in-plane shear and compression, recrystallized grain coarsening occurs due to variations in recrystallization kinetics and shear-induced enrichment of cube-oriented grains promotes selective boundary migration. These findings clarify the role of deformation modes in controlling recrystallization microstructures in ribbon-structured aluminum alloys.