Investigation of mechanical and microstructural properties of pure copper processed by combined extrusion-equal channel angular pressing (C-Ex-ECAP)

Abstract

Severe plastic deformation processes (SPDs) have been developed over the past decades to produce bulky parts with proper mechanical and microstructural properties. Equal-channel angular pressing (ECAP) is a method in which a metal is subjected to severe plastic straining through simple shear. The combined extrusion-equal channel angular pressing (C-Ex-ECAP) is proposed in this paper as a new method of SPD. This process is a combination of extrusion and ECAP processes. The new process contains two shear zones which can lead to UFG structure in fewer passes compared with ECAP. In the proposed method, there is the capability of fabricating longer specimens because of the presence of the extrusion process. This investigation has been performed up to six passes, and the microstructural, mechanical, and electrical properties have been studied in the deformed workpieces. The samples produced in six passes of this process showed a 480% increase in yield strength compared to the annealed sample, and a decrease in grain size from 18 μm to 820 nm, as well as an increase in hardness from 41.8 to 125 HV. The electrical conductivity study also showed that the six-pass specimens had a 5% reduction in electrical conductivity compared to the annealed specimens.