Effect of the Application of Cold Working on the Aging Response and Mechanical Properties of an Al–4Cu–1.4Mg–0.6Ag Alloy

Abstract This study investigates the effect of cold working on the aging response and mechanical properties of an Al–4Cu–1.4Mg–0.6Ag (wt %) alloy. The alloy was produced from pure elemental constituents and processed by casting, homogenization, hot rolling, and solution heat treatment. Following solution treatment, approximately 11% cold rolling was applied prior to artificial aging to produce a predeformed condition, while an undeformed condition was retained for comparison. The aging behavior of both conditions was evaluated as a function of aging time. Microstructural characterization was performed using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). Cold working pronounced the deformation-induced dislocation density and promoted refinement of the second-phase precipitates. EBSD analysis revealed an increase in KAM-derived GND density in the predeformed condition, while SEM observations showed a finer precipitate distribution after aging. XRD analysis confirmed the formation and evolution of Al–Cu-rich and Al–Cu–Mg-containing secondary phases after the aging process. These findings highlight the role of the retained dislocation structure in stimulating heterogeneous precipitate nucleation and regulating precipitate refinement during aging. Finally, the predeformed condition exhibited a significant enhancement in mechanical properties after aging, with the yield strength increasing from 362 to 470 MPa and the ultimate tensile strength from 391 to 503 MPa, while the elongation increased from 2% to 5%. The improved mechanical response is associated with the dual effect of the deformation-induced dislocation structure and precipitate refinement during aging.