Variability in annealing rate of tough-pitch copper wire

Abstract

The effects of changes in process variables during fabrication of hard-drawn wire on the wire annealing rate have been investigated. The rate of annealing is strongly dependent on the temperature of hot-rolling from wire bar slice to rod. Extreme conditions of the time and temperature of the rod anneal prior to drawing can have a considerable effect on the annealing rate, but are unlikely to contribute much to the variability of annealing rates in practice. The ingot size, delay before quenching after hot-rolling, and wire drawing conditions are of little importance. The reasons for the changes in annealing rates are discussed and a suggestion made for improving the wire fabrication procedure in the spiral elongation test.