Comparative study of electrical and mechanical properties of fire-refined and electrolytically refined cold-drawn copper wires

A comparison is made between FRHC (firerefined high-conductivity) and ETP (electrolytically tough pitch) copper wire in cold-drawn samples. Conductivity and mechanical properties are evaluated as a function of the annealing temperature. The fire-refined copper samples with controlled amounts of impurities show the higher annealing temperatures needed to achieve the 100.0% IACS (International Annealed Copper Standard) required to be an electrical conductor. Nevertheless, FRHC copper keeps its mechanical properties for a wider range of annealing temperatures than ETP copper, thereby becoming an interesting alternative for some industrial applications such as trolley wire or fire detection systems. The applicability as trolley wire is evaluated by comparing ETP copper with commercial grades, and an electrical conductivity- tensile strength chart for this application is presented.