Experimental Study on Effect of Equivalent Strain on Evolution Strength of Commer-cially Pure Copper Produced by Equal Channel Angular Pressing

The aim of this study was to investigate the effect of equivalent strain amount on evolution strength of commercially pure copper produced by equal channel angular pressing (ECAP). For this purpose, two ECAP dies with channel angle (∅) 90ᵒ and 110ᵒ, and the angle associated with the arc of curvature (ψ) ~37ᵒ were designed and manufactured. The equivalent strain at each pass of ECAP process is reduced by 25% for ECAP die with ∅ = 110ᵒ compared to ECAP die with ∅ = 90ᵒ. The cylindrical shaped commercial pure copper in the same condition undergone ECAP process at room temperature up to eight passes through two dies, and then the obtained mechanical properties using hardness and compression tests were measured and their changes reported. The obtained re-sults showed that the maximum value of strength and hardness of copper were measured about 390 MPa and 74.9 HB respectively after applying the fifth pass by using ECAP die with ∅ = 90ᵒ. On the other hand, the better mechanical properties were observed in the material produced by ECAP die with ∅ = 110ᵒ. The maximum values of hardness and strength of copper after the eighth pass by using ECAP die with ∅ = 110ᵒ was achieved about 77.5 HB (approximately 51% of the initial sample) and 424 MPa (approximate-ly 63% of the initial sample) respectively. According to obtained results for commercially pure copper produced by ECAP, it can be concluded that the more enhancement mechanical properties such as hardness and strength can be achieved by reducing the applied strain in each pass about 25% and also by increasing the ECAP-ed passes.