Influence of multi-pass rolling and subsequent annealing on the interface microstructure and mechanical properties of the explosive welding Mg/Al composite plates

In this study we investigated the effect of multi-pass rolling and post-rolling heat treatment upon the microstructure at interface and mechanical properties of the explosive welding Mg/Al composite plates. The thin explosive welding Mg/Al composite plates with 2.14 mm in thickness and good surface quality were obtained by 5 passes hot rolling (30% reduction, 400 °C). To meet the requirement of subsequent forming, annealing process was performed. The results indicate that the thickness of interfacial diffusion layer increases with the increase of annealing temperature and holding time. The mechanical properties of composite plates increase first and then decrease with the increase of annealing temperature and holding time. The tensile strength and elongation of the composite plates under 200 °C/2 h annealing condition reach the maximum, which are 285 MPa and 24.5% respectively. Fracture surface morphology indicates that the post-rolling or annealed composite plates all exhibit mixed-mode of ductile and brittle fractures.