investigation of the effect of die parameters on the mechanical properties of pure copper in the combined process of torsional extrusion and ecap

The production of fine-grained materials by severe plastic deformation(spd) methods has made these methods more attractive. the basic conditionfor producing specimens with better mechanical properties and morehomogeneous structure is the application of high and uniform plastic strain.many researchers have tried to modify the existing spds or introduce newtechniques to achieve these goals. in this research, in order to improve themechanical properties of the specimens, a new method is introduced, which isthe combination of the two processes of torsional extrusion and ecap. then,by performing the design of experiments, the optimal die geometric parameters,including the internal angle of the ecap channel ψ , the outer angle of theecap channel , the length of the torsional region l, the ratio of largediameter to small diameter of the ellipse, m, and the torsional angle of the elliptical section, θ, , were obtained 90.5°, 39°, 34mm, 1.65 and 120°, respectively.