Effect of annealing on properties of hot-rolled electrical copper

Experiments on the annealing of hot-rolled oxygen-containing copper in the temperature range of 300–700°C have been performed and the properties and the structure of the metal after this treatment have been investigated. The mechanical properties were studied by constructing tensile stress-strain curves and by determining the ultimate tensile strength, offset yield stress, percentage elongation, reduction of the area, hardness, and modulus of elasticity. The structural studies were performed using optical and electron microscopy. It has been established that the most substantial decrease after annealing at temperatures above 500°C is characteristic of the offset stress (by 62% for copper annealed at 600°C). The spheroidization of pores around the particles of copper oxides at the annealing temperature of 600°C has been revealed. It has been established that the annealing of the hot-rolled copper at temperatures of 500–600°C leads to an increase in the plastic properties of the metal due to the development of the mechanism of the spheroidization of pores and a decrease in the effect of stress concentrators.