Macrosegregation Prediction in Continuously Cast Steel Slabs

Abstract: A prediction model [3] of macrosegregation in continuously cast steel slabs developed by Barber et al from Corus Teesside Technology Centre, UK as an extension of the work of Miyazawa and Schwerdtfeger [4] is presented in this thesis. Improvements have been made in the model to include the effect of many bulges between the supporting rolls induced by the ferrostatic pressure exerted on the solidifying shell by the liquid phase, which were approximated following a deflection of an elastic beam model. The system involved three alloying elements that are 0.1 wt% C, 1.05 wt% Mn, and 0.25 wt% Si as initial concentrations. The iterative numerical methods used to solve for velocity and concentration were the Gauss-Seidel method and Upwind Differencing, respectively.Through a mesh sensitivity analysis, a horizontal growth rate of 1.25 was decided while the grid is equally spaced in the vertical direction over a two-dimensional mid-width plane of the CC22 slab caster configuration at Tata Steel Netherlands in Ijmuiden. Good results were obtained from a validation run despite the assumptions considered. The predicted macrosegregation patterns for C and Mn were to a great extent compatible with the measured ones. The maximum concentrations were predicted at the strand centerline that are 0.13 wt% C, 1.10 wt% Mn, and 0.26 wt% Si. With respect to measured values, it was slightly higher for C by 2.23% error but lower for Mn at 2.28%error, which could be seen negligible. The main factors concluded to influence the strand centerline macrosegregation were initial melt temperature, casting speed, cooling rate and supporting-rolls location when neglecting the mutual interactions between elements. Further improvements can include modifications of the assumptions followed in this model.