Effect of continuous hybrid process on mechanical and electrical properties of rectangular pure copper wire

In this study, a continuous hybrid (CH) process applied with newly designed dies was proposed to manufacture a high strength and high electrical conductivity rectangular copper wire in a continuous way. The 2nd pass CH process with different processing routes, A and C, was numerically and experimentally carried out to check the practicality of the process and to investigate the deformation behavior of the commercially pure copper wire. Electron backscatter diffraction, tension and Vickers micro-hardness tests were employed to study the changes in the microstructure and mechanical properties of the wire. Electrical conductivity was also measured by a four-point probe method. According to the current investigation, the CH process with the new concept dies could impose relatively high plastic deformation without die change during the process and promote the accumulation of dislocation, resulting in grain refinement of the wire compared to the conventional wire drawing (WD) process. The mechanical strength and hardness values of the processed rectangular pure copper wire by the CH process were increased, and the electrical conductivity was relatively maintained compared to the one processed by the WD process. In particular, route C could produce wire with relatively uniform strength distribution. Route A might be adequate for the manufacturing of one-sided hardened rectangular wire such as the contact wire for rail electrification. It is demonstrated that the CH process can be applied to the rectangular wire manufacturing process and might be beneficial to produce high strength and high electrical conductivity copper wire for various applications.