Institute of Materials Science and Metallurgy, Ural Federal University named after the first
President of Russia B. N. Yeltsin, Ekaterinburg, Russia:

Yu. N. Loginov, Professor, e-mail: j.n.loginov@urfu.ru
S. L. Demakov, Assistant Professor
A. G. Illarionov, Assistant Professor
S. I. Stepanov, Researcher

Ural Mining-Metallurgical Company, JSC “Joint Enterprise “Katur-Invest”, Verkhnyaya Pyshma, Russia:
T. P. Kopylova, Technologist

The purpose of this work is definition of differences in impact of broaching and conveyor annealing for the case of heat copper wire treatment. Series of industrial and laboratory experiments with copper wire, obtained by rod drawing, was carried out for comparison of broaching and conveyor annealing effect. 2 mm diameter wire was manufactured at two enterprises, using drawing mills, operating in sliding mode. Deformation degree was 2.8, and relative cross-sectional area reduction was 94%. Broaching annealing was carried out with resistive annealing adapter, mounted into working line of drawing machine with drawing speed of 18 m/s. Thermal effect time was 0.015 sec. In the second method, annealing was carried out in conveyor electrical resistivity furnace in a water vapor atmosphere during 59 minutes. Both methods are characterized by almost similar values of tensile strength and percentage reduction. Tensile strength was increased with respect to hot-rolled condition from 240 MPa to 260 MPa, which can be explained by grain structure grinding and texture state change. At the same time, the yield strength was decreased from 142 MPa to 108 MPa (by 24%). Next series of experiments was set with energy changing, where short broaching annealing was carried out with changing of current in machine annealing adapter with wire drawing with diameter of 1.78 mm at a speed of 25 m/s. Annealing current density was stepwisely changed from 691 to 731 A/mm². After drawing, testing samples were selected and mechanical properties were determined by samples stretching. Dependence of tensile strength function on current density is poorly defined with a minimum difference of maximum and minimum values at the level of ~4%. More signified minimum at the current density of 715 A/mm² was observed for conditional yield strength. Maximum value (149 MPa) differs from minimum value (133 MPa) by 11%. Maximum elongation of 38% was reached at the same current density. Thus, it is shown that increase of plastic properties can be reached by using either conveyor annealing, or optimization of current density in broaching annealing operation. With respect to the broaching annealing, conveyor annealing allows a slightly lower tensile strength of copper and significantly reduces yield strength. Minimum strength properties and maximum plastic properties were reached at a current density of 715 A/mm².

1. Kolachev B. A., Elagin V. I., Livanov V. A. Metallovedenie i termicheskaya obrabotka tsvetnykh metallov i splavov (Metal science and heat treatment of non-ferrous metals and alloys). Moscow : MISiS, 1999. 414 p.
2. Loginov Yu. N., Inatovich Yu. V., Zuev A. Yu. Issledovanie kontaktnogo treniya pri nepreryvnoy goryachey prokatke katanki iz elektrotekhnicheskoy medi (Research of contact friction with continuous hot rolling of electrotechnical copper rod). Proizvodstvo Prokata = Rolled Products Manufacturing. 2010. No. 2. pp. 14–19.
3. Loginov Yu. N., Demakov S. L., Illarionov A. G., Ivanova M. A., Romanov V. A. Struktura sosto yaniya mednoy katanki, poluchennoy pri nepreryvnom protsesse litya – prokatki (Structure of state of copper rod, obtained in the time of continuous casting-rolling process). Tsvetnye Metally = Nonferrous metals. 2013. No. 8. pp. 87–92.
4. Inakazu N., Kaneno Y., Inoue H. Fiber texture formation and mechanical properties in drawn fine copper wire. Materials Science Forum. 1994. Vol. 157–162. pp. 715–720.
5. Loginov Yu. N., Demakov S. L., Illarionov, A. G., Popov A. A. Effect of the Strain Rate on the Properties of Electrical Copper. Russian Metallurgy (Metally). 2011. Vol. 3. pp. 194–201.
6. Wright R. N. Secondary recrystallization in heavily drawn ETP copper wire. Metallurgical Transactions A. 1976. Vol. 7, Iss. 12. pp. 1891–1896.
7. Demakov S. L., Loginov Yu. N., Illarionov A. G., Ivanova M. A., Karabanalov M. S. Effect of annealing temperature on the texture of copper wire. The Physics of Metals and Metallography. 2012. Vol. 113, No. 7. pp. 681–686.
8. Baudin T., Etter A. L., Penelle R. Annealing twin formation and recrystallization study of colddrawn copper wires from EBSD measurements. Materials Characterization. 2007. Vol. 58, Iss. 10. pp. 947–952.
9. Xu Zh., Tang G., Tian Sh., He J. Research on the engineering application of multiple pulses treatment for recrystallization of fine copper wire. Materials Science and Engineering A. 2006. Vol. 424. pp. 300–306.
10. Smiryagin A. P., Smiryagina N. A., Belova A. V. Promyshlennye tsvetnye metally i splavy (Industrial non-ferrous metals and alloys). Moscow : Metallurgiya, 1974. 488 p.
11. Osintsev O. E., Fedorov V. N. Med i mednye splavy. Otechestvennye i zarubezhnye marki : spravochnik
(Copper and copper alloys. Russian and foreign grades : reference book). Moscow : Mashinostroenie, 2004. 336 p.