Vyatka State University, Kirov, Russia

M. Z. Pevzner, Professor, e-mail: mikhailpevzner@yandex.ru

This paper examines the possibility to enhance the production performance by bringing down the power consumption during heat treatment of rolled L63 brass to soft state, which could be achieved through transverse flux induction heating (TFIH) optimization. The rolled L63 brass was produced by semi-continuous casting and hot and cold rolling with intermediate annealing at different thicknesses. Intermediate annealing was performed both in a batch annealing furnace and in two or four linefrequency three-phase TFIH units with successive disposition, built with bottom and top magnetic cores. Magnetic poles of opposite polarity in the opposed teeth of the magnetic core ensured a complete mutual compensation of the opposite axial forces created by the magnetic fields that perform the heating process. When moving from the induction unit to the coiler, the strips were rapidly water sprayed or cooled down relatively slowly in air, followed by a really slow cooling in the coil. Apart from contact and optical pyrometers, flexible chromel-aluminium cable thermocouples were mounted to monitor the strip temperature changing during TFIH annealing and cooling as the strip moved to the coiler, as well as for coil cooling. Strips produced following different processes of cold rolling and annealing were rolled into bands, with a continuous control of the thickness. Through varying the TFIH and cooling parameters, one was able to establish the conditions for reaching an equilibrium state as the result of continuous annealing. This laid the basis for confirming the parameter defining the final structure and properties of the soft rolled brass produced through an energy saving process – i.e. the minimum coiling temperature before the process of slow cooling in the coil starts. The temperature is 560 ^oC. In order to establish the TFIH annealing mode necessary for reaching the above temperature with the equipment used, the author describes how the process mode influences the temperature of a particular type of product at the exit from the induction unit and how such temperature influences the coiling temperature. The developed process, which is based solely on TFIH treatment, enables to:
– obtain rolled brass in soft state irrespective of the process used to produce cold-rolled workpieces;
– minimize the power consumption and maximize the output;
– produce high-precision band through further rolling of annealed strip.

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