Study of the radial direction temperature change law of the coil and control strategy in ultra-fast cooling

With the increasing demand for low-cost and high-performance hot-rolled strips, ultra-fast cooling technology is being rapidly developed. The process temperature control precision is an important factor that determines mechanical properties. Even though the process temperature is controlled, the longitudinal mechanical properties contribute to non-uniformity in thick strips. To reduce the longitudinal deviation, the unloaded coil radial direction temperature distribution under five cooling processes with initial temperatures of 300 °C, 400 °C, 500 °C and 600 °C were systematically investigated. The radial direction temperature deviation change laws affected by the five cooling processes under different initial temperatures were obtained from calculation. With increasing tail special temperature/length, radial temperature deviation decreases gradually. Equations for calculating the temperature deviation of the center-external ring and internal-external ring under different initial temperatures were obtained. The study of temperature distribution in a 10-mm-thick strip provided guidance for the tail process planning in strips of other thicknesses. Based on the research, the progressive-U cooling strategy was suggested to decrease longitudinal property deviation in high-quality steel production. The strategy was successfully applied in a commercial trial production with high accuracy control, laying a solid foundation for high-quality product development.