Numerical model for the minimization of intermixed round bars in a four line continuous caster

The grade transition process in a four line round billets continuous caster was analyzed. A numerical model was developed to determine, quickly and accurately, the length and location of intermixed steel in the bar. The model is based on “tank in series” or “volumes” mathematical models and was calibrated with physical water model measurements and full three-dimensional (3-D) turbulent numerical calculations. Comparison of the model with measurements performed on intermixed steel bars is also presented. The good agreement between these plant measurements and the numerical results validated the model. The model was implemented on PCs with a visual interface that allowed the easy input and output of data, and the program is operated in a steel shop. Finally, the code was employed to evaluate different strategies to fill the tundish during grade transitions. The “double dilution” process, which consists of filling the tundish in two steps, proved to be useful to reduce the amount of downgraded steel.