Abstract
Grain refinement processing by severe deformation, combining Equal-Channel Angular Extrusion (ECAE) processing and conventional tube extrusion, was applied to AZ31 magnesium alloy. By a combination of ECAE processing and tube extrusion, a fabricated tube, with outer and inner diameters of 2 mm and 1 mm, respectively, had fine, homogeneous, and equiaxed grain structure with an average grain size of 1.5μm. Tensile test results indicate that the fine-grained tubes exhibited a superplasticity potential m value = 0.55. The maximum elongation (688%) was obtained at a temperature of 673K and at a strain rate of 1.0×10-4s-1. In addition, compared with tubes only processed by extrusion, ECAE-extruded tubes showed remarkable ductility with an elongation of 245% at a high strain rate of 5.2×10-2s-1. From these results, the effectiveness of new grain refinement processing for fabricating fine-grained narrow tubes was demonstrated experimentally.
