Effect of roll diameter ratio on interfacial microstructure and mechanical behavior of Mg/Al laminated composite plates during differential-temperature asymmetric rolling

To investigate the mechanisms by which the roll diameter ratio in differential-temperature asymmetric rolling controls the microstructure and mechanical properties of the interface in Mg/Al laminated composite plates, AZ31B magnesium alloy and 6061 aluminum alloy were used as substrates. Composite plates were prepared using a single-pass differential-temperature asymmetric rolling process with roll diameter ratios of 1.1, 1.18, and 1.4, and prepared composite plates using a single-pass differential temperature asymmetric rolling process. The microstructure of the interface was characterized, and mechanical properties were evaluated through tensile and interfacial shear tests. The results indicate that as the roll diameter ratio increases, the area of shear stress at the interface first increases and then decreases, leading to variations in the degree of grain refinement at the interface. At a roll diameter ratio of 1.18, the Mg layer undergoes sufficient recrystallization and the substrate texture is weakened, while the aluminum layer exhibits fine and uniform grains and weak stress concentration at the interface, resulting in optimal elongation and bonding strength for the composite plate. This study clarifies the control mechanism of the roll diameter ratio, providing a theoretical basis for process optimization and the fabrication of high-performance Mg/Al composite plates.