Influence of the processing temperature on the microstructure, texture, and hardness of the 7075 aluminum alloy fabricated by accumulative roll bonding

Abstract

The 7075 alloy is an Al-Zn-Mg-Cu wrought age-hardenable aluminum alloy widely used in the aeronautical industry. The alloy was accumulative roll bonded at 300 A degrees C (573 K), 350 A degrees C (623 K), and 400 A degrees C (673 K), and the microstructure, texture, and hardness were investigated. Cell/(sub)grain size in the nanostructured range, typical beta-fiber rolling texture, and homogeneous hardness through thickness were determined in all cases. Misorientation was different at each processing temperature. At 400 A degrees C, the presence of elements in solid solution and the partial dissolution of the hardening precipitates lead to a poorly misoriented microstructure with a high dislocation density and a homogeneous beta-fiber texture of low intensity, typical of intermediate degrees of rolling. At 350 A degrees C and 300 A degrees C, highly misoriented microstructures with smaller dislocation density and intense heterogeneous beta-fiber rolling texture are observed, especially at 350 A degrees C, wherein the degree of dynamic recovery (DRV) is higher. Hardness of the accumulative roll bonded samples is smaller than that of the starting material due to particle coarsening, and it is affected by solid solution and/or by fine precipitates produced by reprecipitation of the elements in solid solution.