Effect of ECAP die angle and route type on the experimental evolution, crystallographic texture, and mechanical properties of pure magnesium

Abstract

Abstract In the current study, the effect of equal channel angular pressing parameters such as die route type and die angle were studied. Billets of pure magnesium (Mg) were processed successfully through up to 2-passes of different routes, A, Bc, and C, using equal channel angular pressing dies with different internal angles of 90° and 120° at 225°C. The crystallographic texture and microstructural evolution were investigated using electron back-scatter diffraction. The Vickers microhardness and tensile properties were investigated, analyzed, and linked to the microstructure and crystallographic texture as well. The as-annealed condition revealed relatively coarse equiaxed grains coupled with some extra-elongated grains with average grain size of 6.338 µm. Processing through 2-passes formed an ultrafine grain structure and recrystallized fine grains. This decrease in grain size was associated with hardness and tensile strength enhancement as compared with the as-annealed Mg counterpart. ECAP processing through the 90° die revealed that 2-passes of route Bc was more effective in grain refinement compared to routes A and C, and it reduced the average grain size by 76.45% compared to the as-annealed counterpart. On the other hand, for the ECAP die with 120°, route A was more effective in grain refinement compared to the other routes. Processing through 2-passes of route C resulted in a stronger texture compared to the other routes with momentous rotation for the texture components. Processing of 2-A, 2-Bc, and 2-C through the 90°-die revealed an increase in the Vickers Hardness (HV) of 76.9, 96, and 84.6%, respectively, compared to the AA counterpart. In addition, the tensile findings revealed that the 90°-die resulted in higher ultimate tensile strength coupled with a drop-in ductility compared to the 120°-die. Furthermore, ECAP processing through the 90°-die led to improvement in the ultimate tensile strength by 14.1, 38.4, and 43.75%, respectively, coupled with improving the Mg ductility by 80.9, 73.5, and 47.6% through processing via 2-A, 2-Bc, and 2-C, respectively, compared to the as-annealed counterpart.