In this article, a coupled three-dimensional mathematic model is established to describe electromagnetic field, fluid flow, heat transfer and solidification in a round bloom continuous casting mold with electromagnetic stirring (M-EMS). The interaction between the induced flow and the impinging jet from a straight-through submerged entry nozzle (SEN) of the caster is numerically analyzed. The results show that the electromagnetic force appears to be circinate at the cross section of the round bloom. Moreover, the flow of the melt is characterized by a dominant swirling movement along the azimuthal direction in the horizontal plane with M-EMS. However, the swirl flow velocity decreases remarkably when solidification is taken into account. With the increase of stirring intensity, the steady flow becomes unstable accompanying with the bias flow, and the temperature distribution is unsymmetrical in the mold. The significant swirl flow with M-EMS prevents the superheated jet moving downward and weakens the invasion depth of the jet, and thus the location of the hot zone in the mold moves up evidently.

In this paper, a compensation control model of secondary cooling process of billet continuous casting for quality steel has been presented. The effects on the spray control of the various parameters such as steel superheat, casting speed, cooling water temperature and chemical component of steel were considered. The parameters of control model were determined to associate with the two‐dimensional heat transfer equation and solved by finite‐difference method. Effects of steel superheat and cooling water temperature on surface temperature, solidification structure and solidifying end point were discussed. Results indicate that steel superheat significantly affects solidification structure and solidifying end point but has a little effect on slab surface temperature. Moreover, secondary cooling water temperature affects surface temperature and solidifying end point but has a little effect on solidification structure. The surface temperature and solidifying end point can be maintain stabilized through applying the compensation control model when steel superheat and cooling water temperature vary. The models have been validated by industrial measurements. The results show that the simulations are in very good agreement with the real casting situation.

In the current paper, Methods of enlarging the area for the distribution of segregation solutes were introduced to mitigate center macrosegregation in steel billets and steel slabs during continuous casting process, which cost less and have significant effect. The location of center macro-segregation is relative to the shape of liquid-core at the solidification end during steel continuous casting. A method of dissymmetrical cooling on different surfaces, by which the area for the precipitation of segregation solutes was enlarged, was introduced to mitigate the center macro-segregation in billets during continuous casting process. Method of optimizing the uniformity of solidified shell in the transverse direction was introduced to mitigate the center macro-segregation in steel slabs. The uniform cooling intensity along the transverse direction guaranteed a regular solidification end in the continuous casting slab, which aided in the effective application of dynamic soft reduction technology. A relevant 2-D heat transfer model was developed for the optimization of uniform solidification. The current method was applied to the industrial slab continuous casting using the heat transfer model. The results indicated a better industrial slab quality with much less center macro-segregation after the use of the method.

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