Microstructure and bonding properties of magnesium alloy AZ31/CP-Ti clad plates fabricated by rolling bonding

In the present work, lightweight AZ31/CP-Ti clad plates were successfully fabricated by the same temperature rolling (STR) and the differential temperature rolling (DTR), a new method, in which only the titanium layer was heated. The effects of the rolling process on the shear strength, bonding mechanism and distribution of thickness ratios of the AZ31/CP-Ti clad plates were investigated. After the experiment, it was found that a good bonding strength of clad plate was obtained via STR method, and DTR method allowed roll bonding of a soft Mg and a hard Ti metal plate with homogeneous deformation. The results indicated that when the rolling temperature was 500 °C and the rolling reduction was 61%, the shear strength of the AZ31/TA1 clad plates reached a peak value of 92 MPa. The fracture surfaces of the clad plates presented ductile fracture characteristics with high bonding strength, and the fracture mainly occurred in the transition zone from magnesium oxide to magnesium matrix. The bonding mechanism of the clad plates was different under the two types of processes: the bonding interfaces of the clad plates produced by STR were approximately a straight interface where the prolonged contact heating and rolling pressure caused diffusion to be the main bonding mechanism. However, a large corrugation with serrate-shaped morphology was observed at the bonding interface when the clad plates were generated by DTR, and cracks appeared on the titanium side with magnesium metal extruding into the cracks; furthermore, the DTR bonding interfaces showed mechanical meshing characteristics.