Numerical Simulation Of Electroslag Remelting And Round Billet Continuous Casting

This research consists of two parts. The first part is the numerical simulation for the heat transfer and the solidification in the electroslag remelting(ESR), and the second part is the numerical simulation for the flow field, the temperature field and the solidification structure in the round billet continuous casting.In the first part, the ProCAST software was applied to predict the temperature field and the solidification process in the electroslag remelting(ESR). At the beginning of electroslag remelting, the main heat output comes from the forced convection of the bottom of water cooling, heat transfer is greater at axial direction. With the liquid drops constantly dripping from the slag pool, the liquid-metal pool rises gradually, the radial heat transfer of crystallizer side occupies a larger proportion, and the depth of liquid-metal pool becomes deeper and deeper. When the depth of liquid-metal pool achieves a certain height, the shape of liquid-metal pool changes a little. At the bottom, the fine crystalline structure is formed at first. Then the columnar crystals region appears in the vertical direction. Finally, an inverted V-shaped columnar crystal region is formed. The liquid-metal pool becomes deep and wide with the increase of the temperature of slag pool; the depth of liquid-metal pool becomes shallow with the increase of the coefficient of heat transfer and the decrease of the remelting rate; low temperature of slag pool and large coefficient of heat transfer are two key factors to promote the formation of equiax grain, but remelting rate has a little effect on the solidification structure.In the second part, round billet continuous casting process was simplified. And then a simplified mathematical model was developed to predict the flow, heat transfer and solidification structure. At last, the effect of casting speed was discussed. Because of the single-hole straight submerged nozzle, liquid steel flows straight down into the casting mold, flow rate gradually decreases. The liquid steel near the center always moves downwards until reaching the maximum impact of depth, but the liquid steel far away from the center deviates during their movement and then flow upwards after contacting with the mold wall, then forms the vortex near the casting mold wall. There is no side-hole for straight submerged nozzle, so the center in the recirculation region is far away from the free surface, and the flow rate is relatively small at the free surface. It should be noted that the few of fresh liquid steel passes by free surface so that the temperature changes greatly at free surface. At the same time, during the continuous casting process for the round billets, the round billets has the fine equiax grain region, the columnar crystal region and the equiax grain region from the surface to the center.