During a CC process, molten steel is continuously poured into the water-cooled mold through SEN, which forms a solidified shell of sufficient thickness when slab is pulled out.
Slab quality, particularly regarding surface and internal cracks, is closely related to the turbulent flow in the mold and the heat transfer through the heat face on the mold copper plate during solidification in a CC process.
If thermal stress by temperature gradient in the mold copper plate is excessive, strain occurs in the mold copper plate, and with increase in casting time and constant iteration of heating and cooling processes on the copper plate, microcracks are generated, which might cause an irretrievable accident in the copper plate.
In the past, for most numerical simulations on temperature field in the mold copper plate, empirical formulas on already-developed heat flux density or the value obtained by applying the temperature measured from the thermocouple inserted in the mold copper plate to the inverse finite-element model were used, and the heat exchange coefficient between the cold face on the copper plate and cooling water calculated by means of Dittus-Boelter’s formula was applied to the boundary condition of the cold face on the copper plate.
These methods have the advantages of saving time for simulation calculation, but since the temperature value measured from the thermocouple inserted in the mold is not precise enough, it is difficult to ensure the accuracy of simulation results and to reflect the effect of as many factors as when using empirical formulas.
Moreover, few studies have been found on the temperature field in the mold copper plate with heat contact resistance like mold flux, allowance, and coating layer under consideration by a one-quarter model of Full SEN-3D FEMM.
Om Sang Chol, a section head at the Faculty of Materials Science and Technology, has simulated the temperature field in a Full SEN-3D FEMM considering the flux character of molten steel through SEN, the mold flux, the coating layer and the stainless back plate. In addition, he has carried out a simulation on the temperature field and thermal stress and strain on mold copper and stainless back plates by applying the maximum heat flux density on the heat face of copper plate obtained from the simulation to the element model of the mold copper plate.
Thus, he was able to determine reasonable design factors for water slot structure on a mold copper plate.
If further information is needed, please refer to his paper “A simulation method for the optimization of cooling water slot structure in slab continuous casting mold combined with submerged entry nozzle” in “The International Journal of Advanced Manufacturing Technology” (SCI).
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