Effect of annealing process on interfacial microstructure and mechanical properties of Zn/AZ31/Zn clad sheets

Abstract Zn/AZ31/Zn clad sheets were prepared by hot rolling process. The effects of annealing temperature and time on the interface microstructure and mechanical properties of the clad sheets were investigated. The results show that the annealing temperature has great influence on the formation of interfacial diffusion layer.The interfacial diffusion layer cannot be formed at low annealing temperature, but good metallurgical bonding interface can be obtained,which is composed of Mg4Zn7 and MgZn2 phases annealed at 200 ℃. The higher annealing temperature (300 ℃) leads to the precipitation of the brittle Mg2Zn11 phase at the interface, thereby inducing microcracks along the interface. At the same annealing temperature, the extension of time only affects the thickness of the diffusion layer, and has no effect on its phase formation. The strength of the sheets is reduced after annealing, but the plasticity is improved. The clad sheets obtain better mechanical properties when annealed at 200 ℃ for 1 h.