Elucidating the effect of accumulative roll bonding deformation routes on the electrochemical and passive behavior of AA2024 aluminum alloy

Abstract

The correlation of deformation route changes and crystallographic texture with the electrochemical properties of AA2024 aluminum alloy in a phosphate buffer solution (pH = 9) was investigated. Commercial 2024 aluminum alloy sheets underwent up to eight cycles of processing at room temperature using two different deformation routes: accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB), involving a 90° rotation around the normal direction (ND) axis between each cycle. The ARB-processed AA2024 alloy exhibited an elongated lamellar ultrafine-grained structure and included texture components such as Copper {112}<111>, Dillamor {4 4 11}<11 11 8>, S {123}<634>, Brass {110}<221>, and P {110}<221>. Meanwhile, the CARB-processed AA2024 alloy had a near equiaxed ultrafine grain structure with a size of 150–100 nm and texture components including Copper {112}<111>, Brass {011}<211>, P {110}<221>, Rotated Cube {001}<110>, S {123}<634>, and Goss {011}<100>. The study revealed that the variation of electrochemical properties during different deformation routes was closely linked to texture manipulation and microstructure. The lamellar ultrafine-grained structure resulting from the ARB processing route increased the corrosion current density, whereas the opposite trend was observed in the CARB route. Moreover, it was concluded that the combination of uniform grain refinement and high-intensity {011} orientation textures achieved through CARB processing provided ideal conditions for forming a passive layer with superior protection properties.