Microstructure refining and property improvement of ZK60 magnesium alloy by hot rolling

The as-cast ZK60 Mg alloy ingot with mean grain size of 278 μm after solution treatment was subjected to severe plastic deformation by multi-pass hot rolling with decreasing temperatures. The process facilitated steady grain refinement by dynamic recrystallization with increasing rolling deformation, and the final grain size was reduced to 7.2 μm by 6 rolling passes. Tensile experiments demonstrated that the yield and ultimate strength of the finished plates were isotropic, with the former being about 202 MPa and the latter 307 MPa in both the rolling and the transverse direction, respectively. Electron backscattering diffraction revealed that the finished plates presented homogeneous microstructure and texture pattern, which well explains the observed strength isotropy. Furthermore, it is shown that the as-rolled finished plates don't need the conventional long-time T5 aging treatment, and this can simplify the process flow and help to improve the efficiency for industrial production.