A combination of high electrical conductivity and mechanical strength in AA1070 commercially pure aluminum wires fabricated by KoBo extrusion

Abstract

Abstract In this work, the effect of KoBo extrusion process parameters on the extrusion force, microstructure, mechanical properties and electrical resistivity of wires fabricated from AA1070 commercially pure aluminum, is analyzed. It is found that applied parameters of the KoBo extrusion process have a strong impact on changes in the extrusion force. The smallest variation of the extrusion force was recorded for the KoBo extrusion conducted with a small oscillation angle and a high extrusion rate. The relatively small alteration of the extrusion force results in a more homogeneous microstructure and mechanical properties of the wires. As compared to the material in the annealed state, the KoBo extruded wires exhibit almost two-fold higher ultimate tensile strength and only a slightly lowered electrical conductivity. The best combination of electrical conductivity and mechanical strength was 60.3 % International Annealed Copper Standard and ultimate tensile strength of 152 MPa, respectively. These results are highly competitive to those reported for AA1070 aluminum subjected to other continuous plastic deformation methods (e. g. the cryorolling combined with a heat treatment). A high electrical conductivity and enhanced mechanical properties (in respect to the as annealed material), clearly indicate that the KoBo extruded AA1070 wires are potentially useful for moderately loaded electrical engineering applications.