Effect of deformation methods on microstructure, texture, and properties of a Cu–Mg alloy

Abstract

The effect of cold working by drawing, rolling, or equal channel angular pressing (ECAP) on the microstructure, the texture, the mechanical properties, and the electrical conductivity of a Cu-0.25%Mg alloy was investigated. The plastic deformation led to the development of continuous dynamic recrystallization that was accompanied by strain-induced low-angle boundary formation and their transformation into high-angle boundaries with straining. The elongated grains evolved after drawing. Sheet rolling provided pancaked ultrafine grain formation assisted by the development of microshear bands. After ECAP almost equiaxed ultrafine grains formed readily inside the deformation microbands. The rapid kinetic of grain refinement assisted by geometric dynamic recrystallization during cold rolling and drawing led to the formation of ultrafine grains with transverse sizes of about 0.20 μm and 0.43 μm, respectively, while the grain size in the ECAP samples was 0.88 μm after total strain of 4. The deformation microstructures led to the significant strengthening resulting in the ultimate tensile strength of about 670 MPa after drawing or rolling to total strain of 4 and 625 MPa after ECAP to total strain of 9.2. Elongation slightly decreased from 21% to 19% after ECAP and dramatically degraded to 6–8% after drawing or rolling. A decrease in elongation was accompanied by a linear increase in the fraction of specific texture components. Electrical conductivity gradually decreased by about 6–10% IACS with straining regardless of deformation method. The strengthening mechanisms and the conductivity variation during deformation are discussed.