Effect of Equal Channel Angular Pressing Parameters on Grain Refinement for Magnesium and Its Alloys: A Review

Equal Channel Angular Pressing (ECAP) technique is widely used to refine grains in metallic materials, including magnesium and its alloys. This paper reviews the grain refinement data for various magnesium alloys achieved through ECAP processing. The data are analyzed to explore the effect of ECAP parameters on grain refinement effectiveness and provide us with some guidelines for selecting appropriate values for the processing parameters. The parameters studied include the internal channel angle ϕ, the outer arc angle Ψ, the pressing temperature T, the number of ECAP passes N, and the type of ECAP processing Route. Some key observations and general trends were obtained based on the analysis: (i) route Bc is generally the most effective processing route to generate finer grains and it is the most commonly used pressing route in the literature; (ii) the most commonly selected ECAP temperature falls between 200 °C and 300 °C; (iii) ECAP processing often refines grains the most during the first pass; and (iv) the most commonly used number of ECAP passes is less than 8.