Study of the annealing process for the drawn fine copper wire

Abstract

The objective of this research was to study the behaviour of annealing factors, which affected on the mechanical properties of copper drawn wire used for producing low voltage cable. 8mm diameter of copper rod was reduced into 2.6, 0.6, and 0.08 mm diameter, which were the percentage of cold work of 89.44, 99.44, and 99.99%, respectively. The drawn wire of 0.08 mm, then, were annealed. The annealing method studied was the single phase-continuous electrical resistance annealing, 3-sheave type. The factors that involved with this type of annealing was the electrical voltage, wire speed, and coolant temperature. For the annealing process, there were nine experiments, which were varied the annealing voltage at 25, 27, 29, 31, 33, 35, 37, 39, and 41 and fixed wire speed cooling temperature at 2,000 m/min and 50ํC, respectively. The annealed drawn wires were analysed. The products of both drawing and annealing process were characterised for mechanical properties and microstructure being percentage of elongation, tensile strength, grain size, and porosity. The experimental results found that (1) The increasing of percentage of cold work increased the tensile strength but decreased the percentage of elongation and grain size of cross-sectional area of drawn copper wire. (2) The percentage of elongation and grain size of drawn wire increased with the increasing of annealing voltage. (3) The appropriate annealing voltage, which the wire was not discoloration, Was 37 volt and provided the percentage of elongation of 24.1. (4) The large size and high amount of porosity decreased the wire strength, which the lowest strength was 24.28 kgf/mm2 found at the experiment of 33V that was mostly found the porosity.