Enhanced strength of copper-steel composite plates prepared by laser assisted rolling bonding process

This study investigated the interfacial characteristics and strengthening mechanisms of copper-steel composite plates prepared via laser assisted rolling bonding process. The wavy-like interface without defects (such as pores and cracks), together with the ∼0.2 μm thick FeO layer characterized with discontinuous distribution and localized amorphous structure, is obtained by laser assisted rolling bonding process even if the absence of protective gas. According to the gradient-assisted heating effect of laser and rolling deformation, the grain morphology transitions from fine grain near the interface to fibrous grains adjacent to the rollers in copper side, and a gradient-phased structure with the martensitic transformation occurred at the location near the bonding interface can be observed in the steel side. The semi-coherent and incoherent interfaces ensure the superior interfacial bonding strength with the value of ∼120 MPa to ∼150 MPa, and the synergistic effects of high dislocation density, excellent coordinated deformation capability of oxides and strong dislocation hindrance by oxides contribute to the ∼837 MPa tensile strength. Therefore, the laser assisted rolling bonding process is a promising way to form the layered metal composite plates with the characteristics of short-process and high-performance.