Effect of Two-Pass Differential Speed Rolling and Annealing on Microstructure and Properties of 5083Al/AZ31BMg/5083Al Composite Sheets

Abstract

This study successfully fabricated 5083Al/AZ31BMg/5083Al trilayer composite plates with superior interfacial bonding strength and tensile properties using a two-pass differential speed rolling (DSR) process, outperforming conventional constant speed rolling (CSR). The DSR was conducted with speed ratios of 5:4 and 4:5, achieving a total reduction of 65.9% (55 + 22%), followed by annealing at 200°C for 1 h. The rolled composite plates before and after annealing were characterized in terms of tensile properties, interface bonding strength, interface structure, and the microstructure evolution of the Mg matrix near the interface. DSR introduces intense shear strains, which activate the prismatic slip and shear bands in the Mg matrix, and fragment the interfacial metallic compounds (IMCs), aligning them at a specific angle to the interface. The developed shear bands caused poor tensile properties in the DSR state. While the warped and discrete IMCs, together with the increased number of new Mg/Al bonding interfaces, significantly enhanced the interfacial bonding strength of the composite sheet. Post-annealing made the DSR processed sample recrystallized within shear bands, forming a bimodal grain structure that enhanced ductility while preserving strength. In contrast, the CSR process generates crossing shear bands that promote recrystallization for good tensile strength; however, it produces coarse, continuous IMC plates parallel to the interface that lower the bonding strength. These findings offer valuable insights into the industrial application of Al/Mg/Al composite sheets.