Effect of differential speed rolling on microstructure and mechanical properties of an AZ91 magnesium alloy

Severe deformation by differential speed rolling (DSR) with a high-speed ratio could be successfully imposed on the AZ91 plate to produce thin sheets with submicron grain size and good planar isotropy. The sheets exhibited a good combination of high strength and high ductility, showing yield stresses of ∼327 MPa and tensile elongations of 9–11%. Comparison with other severe deformation processes indicates that DSR process is advantageous over ECAP process in obtaining higher strength and over ARB process in obtaining higher ductility. Moreover, the current DSR is a continuous process as well as a convenient method of imposing severe deformation on thin Mg sheets.