Influence of crystallographic texture on the strength and electrical conductivity of ultrafine-grained copper

The paper covers the study of the influence of equal-channel angular pressing (ECAP) on the structure, crystallographic texture, mechanical properties and electrical conductivity of Cu-ETP copper (Russian analogue – M1), as well as the dependence of these characteristics on the orientation of the measurement direction relative to the cross-section (from −45 to 90°). The specific electrical conductivity and strength characteristics of the material in the as-delivered condition (hot-rolled) and the effect of annealing at a temperature of 450 °C of the original sample are investigated. Mechanical tests for uniaxial tension, a study of microhardness using the Vickers method and a study of specific electrical conductivity based on measuring the parameters of the vortex field excited in the surface layers of the body are carried out. It is found that ECAP processing leads to a significant increase in the ultimate tensile strength to 425 MPa compared to the initial state of 300 MPa. The maximum tensile strength of 425 MPa is achieved at orientation angles relative to the ECAP cross-section of −45°. A significant increase in microhardness to 1364–1405 MPa, tensile strength to 350–425 MPa and electrical conductivity to 101.4–102.4 % IACS is a consequence of the selected directions of cutting the samples relative to the ECAP axis. This indicates the dependence of both mechanical and electrical properties of ultrafine-grained samples on the crystallographic texture orientation. A Cu-ETP copper sample subjected to ECAP with a cutting angle deviating from the ECAP cross-section of the sample by 7.5° has the most optimal crystallographic orientation. In this case, the values of microhardness and electrical conductivity reached 1405 MPa and 102.4 % IACS, respectively.