On the Effect of ECAP Processing Temperature on the Microstructure, Texture Evolution and Mechanical Properties of Commercial Pure Copper

Abstract

In the last decade, a large demand of the industries for a material with high level of strength and conductivity is widely undergoing. Several types of metals which includes, silver, copper, gold and aluminum are largely utilized due to their level of electrical conductivity. In term of cost comparison, the aluminum and copper are the most reasonable price with the advantage of this conductivity. However, these materials have lower electrical conductivity with compared to other metals due to two reasons. The first one, the impurities that enlarge the electron scattering by thermal vibrations of the crystal lattice. The second one, the attendance of structural imperfections which contain grain boundaries and dislocations [1-3]. The Ability of balancing this issue is via obtaining of the both pure materials with improvement of mechanical strength. The enhancement of various metals strength such as copper can be reached by heat treatment and the addition of other alloying elements. However, this technique can lower the ductility and electric conductivity [4]. The other successful way is by improving the structure to obtain ultrafine-grained (UFG) and a large grain boundary area [5,6]. These outcomes can be reached by undertaken severe plastic deformation method (SDP) [613]. Severe plastic deformation technique has been used widely nowadays due to their influence on the microstructure behavior. The production of ultrafinegrained microstructures and the deformation of metallic and alloy materials can be achieved by this process. The most applicable processes of the (SDP) is equalchannel angular pressing (ECAP) due to their highly effective of fabricating different types of ultrafine-grained materials [14-20], producing nano-crystalline bulk materials [21], improving both mechanical and physical properties [5], achieving the homogenously deformation of bulk material [22,23] and the dealing with the mechanics of metal flow and the microstructural evolution [20]. Furthermore, the ductility of material can be enhanced by utilizing ECAP, since the enhancement of a duplex microstructure shaped by nanometric grains sized coupled with micrometric or UFG without sacrificing the martials strength [24]. The ECAP method can utilized various sample's shape such as rectangular, square, or circular. By unlimited number of passes throughout the die, the severe shear deformation of microstructure can be obtained during this way without dramatic changes in the dimensions. As a In this study, the severe plastic deformation (SPD) behavior of commercial-grade pure copper processed using equal channel angular pressing (ECAP) was investigated. The copper rods were processed for up to 4 passes, both at room temperature and 200 C. The microstructure and texture evolution were studied using a field emission scanning electron microscope (FESEM) equipped with an electron back scattered (EBSD) detector. The effect of ECAP processing on the tensile properties, micro-hardness, and impact toughness was studied. After 1 pass, the average grain size of the rods was determined to be 2.694 and 3.9066 μm at room temperature and 200 C, respectively. In addition, after 4 passes through ECAP, the strength of the ECAPed samples increased to 381 MPa, and 330 MPa at room temperature and 200 C, respectively; and the Vickers’ micro-hardness at the peripheral areas increased to 158, and 126, respectively. In the other hand, the experimental findings revealed that the number of ECAP passes has insignificant effect on the impact energy.