Abstract
The effects of pre-heating at 873 K on softening during annealing of cold-drawn copper wires containing lead were studied in relation to lead concentration. Annealing behavior of cold-drawn copper wires containing lead and antimony or lead and nickel were also studied. Hot-rolled copper wires after pre-heating were cold-drawn to 90% reduction and annealed at 293-673 K for 3.6 ks. The annealed copper wires were subjected to tensile tests and observations of the microstructure.
The half-softening temperature of cold-drawn copper wires without the pre-heating increases with lead concentration from 1 to 590 mass ppm and the half-softening temperature of the pre-heated and cold-drawn copper wire is lower than that of the cold-drawn wire without the pre-heating. The enhancement of softening is due to recrystallization enhancement by the decrease of lead dissolved in the copper matrix and the formation of Pb-oxide.
When lead and antimony coexist in copper, the enhancement of softening is suppressed. When lead and nickel coexist in copper, the softening rate is not affected.
The effects of lead on the enhancement of softening and the effects of antimony and nickel on the enhancement of softening during annealing of cold-drawn copper wire containing lead are clarified.
