Effect of annealing process on microstructure and properties of pure copper wire T2
Mao Xiqin, Xiao Qiulei, Ou Meigui, Liang Yu, Long Wei
2020, 45(7):
7-10.
doi:10.13251/j.issn.0254-6051.2020.07.002
Abstract
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T2 pure copper wire was obtained by cold drawing, then low-temperature long-term annealing (400 ℃×60 min) and high-temperature short-term annealing (at 850 ℃ for 20, 40, 60 s, respectively) tests were carried out. The microstructure, mechanical and electrical properties of the wires in different states were studied by means of OM, SEM, universal testing machine and DC wheat stone bridge. The results show that the fibrous structure of the cold drawn T2 pure copper wire forms recrystallized grains after annealing accompanied by annealing twins. With the increase of annealing time at 850 ℃, the recrystallized grains of the wire grow continuously, and the grains morphologies tend to equiaxed, and the uniformity of wire structure is improved. The average tensile strength of annealed wire is about 57.1% of that of drawn wire, the percentage elongation after breaking was about 10 times of that of drawn wire, after annealing at 400 ℃ for 60 min, the conductivity of the wire is only 0.3% higher than that of the drawn wire; after annealing at 850 ℃ for 20,40 and 60 s, the average conductivity of the wire is 5.2% higher than that of the drawn wire. The mechanical and electrical conductivity properties of the wire after high-temperature short-time annealing are not only better than low-temperature long-time annealing, but have a higher annealing efficiency. In conclusion, the wire annealed at 850 ℃ for 40 s has high mechanical properties and electrical conductivity.
