Rolled stock thermomechanical treatment in line of 250 wire-rod mill

Abstract

To provide a technical possibility of regulated rolling in combination with intensive cooling of rolled stock, the modernization of 250 wire-rod mill of PAO “Izhstal” was accomplished. Within the modernization actions were carried out to increase the rigidity of finish section stands, to assemble the lines of thermo-deformation strengthening (TDS) and accelerated cooling (Ter-mex). The adopted schemes of the equipment arrangement at the mill modernization enabled to dispose the new equipment at the existing site in line of the mill, which provided a smooth billet travelling. To realize the rolled stock accelerated cooling, elements of water cooling system were installed after the sizing stand section before the cooling bed. The control of cooling process was arranged by an automated system, including several sensors, installed along the whole TDS line. To control the rolled stock tension, a horizontal spooler was installed between the last stand and before the shears and the first stand after the TDS line. Indices of strength, plasticity and impact toughness of rolled stock of carbon and low-alloyed steel, reached at the controlled rolling with application of accelerated cooling TDS, quoted, as well as the rolled stock microstructure at regular rolling and rolling with TDS application. For a series of carbon and low-alloyed steels, a technology of rolled stock production was elaborated, excluding the necessity of thermal treatment by a separate heating operation. Systematized by steel grades groups target parameters were formulated, which should be provided by controlled rolling mode usage with rolled stock TDS application.