Response mechanism of matrix microstructure evolution and mechanical behavior to Mg/Al composite plate by hard-plate accumulative roll bonding

In the traditional accumulative roll bonding (ARB) process of heterogeneous composite laminates, due to the excessive strain caused by accumulative roll bonding, many problems such as reduction of plasticity and cracks on the edge of composite plates cannot be ignored while increasing the strength. In this paper, a method of developing a Mg/Al composite sheet by hard-plate accumulative roll bonding (ARB (HPR)) is proposed. The addition of hard plate can change the stress state of the composite laminate during the rolling process, The shear stress in the rolling direction is partially converted into the compressive stress in the normal direction, which then increases the welding pressure between the heterogeneous composite laminates, the interface is closely bonded, and the warpage and edge crack caused by severe plastic deformation is significantly reduced. The results show that this method can significantly improve the tensile strength and plasticity of the composite laminate. The yield strength is 226 MPa, and the elongation is 21.5%, which is substantially higher than that of the traditional accumulative roll bonding. Many dynamically recrystallised grains were formed, the grains were uniform and delicate, and the grain boundaries were clear. To sum up, the Al/Mg composite sheet rolled by hard-plate accumulative roll bonding has improved in many aspects, such as mechanical properties and sheet formability, which provides a new idea for the research on the forming and manufacturing of heterogeneous composite laminates.