comparison of hardness values of various specimens with different geometries and material properties after ecap

nowadays, equal channel angular pressing, known as the ecap process, is one of the most popular methods for manufacturing ultra-fine grained (ufg) materials. in this paper, ecap process has been carried out on pure copper and 6012 aluminum alloy up to six passes by route . principal attention was paid to the influence of parameters such as diameter, material, and the height of billet on mechanical properties and hardness homogeneity induced by the process. moreover, microhardness measurements carried out on the cross-section of the ecaped copper and aluminum showed 103 and 46 % increase in hardness magnitude and 115 and 50% in  after the sixth pass. furthermore, hardness distribution got better for aa6012 and worse for copper after six passes of ecap. finally, a computer program was used to obtain effective strain distribution imposed to across the width at the center of the samples after one pass. the results obtained from the 3d fem method were compared with the hardness measurement and showed good conformity with experimental results, which indicated that homogeneity strain improves as increasing the diameter and height had no conspicuous effect on value and homogeneity of strain and hardness of the central region of specimens.