effect of hpt and cgp processes on the copper me-chanical properties

one of the most common methods for production of ultra fine grained materials is severe plastic deformation (spd). in this study, constrained groove pressing (cgp) and high pressure torsion (hpt) processes as effective methods of severe plastic deformation for the strain imposed on the pure copper were used. this paper presents the results of an experimental research, to review the influence of cgp and hpt processes of the mechanical properties such as hardness and tensile on copper samples has been done. the results of tensile and hardness tests represented that due to applying cgp process, strength and hardness of samples were increased significantly.the results of hpt process showed that hardness in the radial direction is variable and away from disk center in the radial direction continuously increases. of course, in higher pressing steps the slight decrease in strength and hardness is observed, more explanation is given in this paper. finally, comparison results of the two methods, their advantages and limitations of them are studied.