Effect of asymmetric forward rolling (AFR) on the microstructure, texture, mechanical properties, and Portevin–Le Chatelier behavior of AA5052 alloy

This study investigates the effects of asymmetric forward rolling (AFR) on the microstructure, texture, mechanical properties, and Portevin–Le Chatelier (PLC) behavior of AA5052 aluminum alloy sheets. With increasing strain from 10% to 50%, the microstructure exhibited a progressive increase in deformation bands. At 70% AFR strain, these bands became indistinguishable due to significant thinning of α grains, accompanied by the formation of numerous subgrains indicative of dynamic recovery (DRV). X-ray diffraction analysis revealed peak shifting to lower angles and broadening with up to 50% strain, attributed to lattice distortion from high dislocation density. Intense DRV in the 50% and 70% AFR-processed sheets resulted in a marked increase in α-fiber texture intensity. However, texture evolution was limited at 70% strain due to the stabilizing effect of second-phase particles. Notably, the shear texture intensity was lower than in prior studies, as no sheet rotation was applied between rolling passes. A microhardness gradient across the sheet thickness at 70% strain reflected inhomogeneous stored strain energy. In contrast, yield and tensile strengths increased consistently with strain, driven by robust strain hardening from gradient strain energy. Uniform elongation reached a threshold of 5% in the 70% AFR-processed sheets. The influence of dislocation accumulation on PLC behavior and stress drops was less pronounced than that of DRV. The Θ-ε curves for 50% and 70% AFR samples showed a reduced slope in the second stage, consistent with DRV effects. Ductile fracture dominated even at 70% strain, with increased dimple formation linked to sub-boundary development, indicating sustained ductility in AFR-processed AA5052 sheets.