Quantitative Study on the Evolution of Microstructure, Strength, and Electrical Conductivity of the Annealed Oxygen‐Free Copper Wires

In the process of electric power transmission, the defects in the copper wire interact with the electrons which results in a thermal effect, accordingly, causing the changes of microstructure and properties of the copper wire. Herein, the evolution of microstructure, strength, and electrical conductivity of the oxygen‐free copper wires annealed at different temperatures is investigated. In addition, the effects of various microstructures on strength and electrical conductivity are quantitatively revealed. In the low‐temperature region (80–150 °C), dislocation recovery is the main reason for the decrease in strength; while, the increase in electrical conductivity is mainly due to the decrease in dislocation density and the transformation of grain boundary from nonequilibrium state to equilibrium state. In the high‐temperature region (above 210 °C), the strength loss is mainly related to the increasing recrystallized grain size and the disappearance of dislocations in the recrystallized region. The increase in electrical conductivity is mainly attributed to the significant decrease in grain boundary density and the further recovery of dislocations.