Advanced temperature control of high carbon steel for hot strip mills

In this paper, an advanced temperature control for the high carbon steel is proposed to obtain the desirable temperature and property of a steel on the run-out table (ROT) process. The temperature model based on the nonlinear heat transfer equation is described to predict the temperature of the steel at each position of the ROT. A cooling stop temperature (CST) concept is proposed to increase the volume fraction of the transformed phase for the high carbon steel. The concept is derived from a time-temperature transformation (TTT) diagram which is measured from the dilatometric experiment. The simulator using the temperature model is developed to achieve the desired temperature, and the effectiveness of the proposed control is also analyzed from the simulation. It is shown through the field test of the hot strip mill of POSCO that the performance with respect to the temperature and the property of the steel is greatly improved by the proposed control technology.