Numerical simulation of the flow, solidification, and solute transport in a billet mold under electromagnetic stirring

In this study, a coupled three-dimensional model of the billet continuous casting mold process was developed to investigate the characteristics of the macroscopic transmission behaviors under different mold electromagnetic stirring (M-EMS) parameters. The mold curvature was also considered during the modeling of electromagnetic and flow fields. The results indicate that the macroscopic physical quantities had nonsymmetrical distributions in the mold because of the mold curvature. However, the influence of mold curvature on the electromagnetic force could be ignored. The horizontal swirling flow caused by the M-EMS became stronger as the current density increased, which enhanced the dissipation of the molten steel superheat and promoted the growth of the solidification shell. However, the flushing of the bias hot jet slowed the growth of the local solidified shell. Meanwhile, the washing effect of the melt flow on the solidification front caused the solute element content near the billet surface to fluctuate. In addition, the distribution of the solute element content became more uneven in the strand transverse direction as the current density increased.

Hydraulic Modeling on Flow Behavior in High-Speed Billet Continuous Casting Mold Considering Hydrostatic Pressure and Solidified Shell

The flow behavior in the mold has a considerable influence on the final product quality of the strand. In this paper, the variation of flow field, level fluctuation, and liquid slag distribution was analyzed by a hydraulic modeling experiment of a high-speed billet continuous casting mold with and without consideration of hydrostatic pressure and a solidified shell. The results indicate that a mold with hydrostatic pressure and a solidified shell possesses an impact depth shallower by 10–30 mm, level fluctuation greater by 3–15%, and more active liquid slag layer at different casting speeds than a mold without them. Moreover, the results of the hydraulic modeling with hydrostatic pressure and a solidified shell agree well with those of the numerical simulation. Therefore, the mold flow behavior modeled with hydrostatic pressure and a solidified shell is closer to the actual behavior than that obtained by models without them. The method in this paper contributes to improving the accuracy of the hydraulic modeling experiment and establishing a foundation for further study of continuous casting.

Melting and Flowing Behavior of Mold Flux in a Continuous Casting Billet Mold for Ultra-High Speed

High casting speed coincides with the development trend of billet continuous casting, which significantly changes the casting characteristics. A mathematical model of the billet mold, which includes multiphase fluid flow, transient heat transfer, and solidification during ultra-high speed of the casting process was developed. The model is first applied to investigate the flow field of molten steel in the mold, studying the influence of steel flow upon the melting and flowing behavior of mold flux. The temperature and velocity distributions of the flux pool that formed above the molten steel surface are described. A parametric study on the melting temperature and viscosity of mold flux on liquid flux thickness and flow velocity is then carried out. Finally, the model is used to derive the relationship between interfacial tension and level fluctuations. The predictions provide an improved understanding of the melting and flowing behavior of mold flux in the billet mold and give the guidance for the design and optimization of mold flux for ultra-high speed of billet casting.