Mould level velocities during continuous casting of round bloom strands with mould-electromagnetic stirring
Sprache des Titels:
Proceedings of 4th International Conference on Process Development in Iron and Steelmaking
In modern continuous casting of round steel blooms rotating electromagnetic fields are commonly employed. Mould-electromagnetic stirrers (M-EMS) are used to excite a rotary motion along the solidification front inside the liquid core of the strand. These velocities shall lead to a better strand surface quality as well as enhancing the transition from columnar to equiaxed solidification. Although the usage of electromagnetic stirrers is widespread, not all effects are fully known or understood.
Due to harsh conditions at the plant measurements are scarce and limited. Water model experiments ? an established alternative for investigating continuous casting of steel ? cannot be used due to the low conductivity of water. Experiments with liquid metals like mercury, Galinstan or wood metal, are either expensive or difficult to conduct. Thus numeric simulations are essential to gain a better understanding of the processes involved in continuous casting with electromagnetic stirring. But numeric simulations should always be validated with either experiments or measurements. While the velocity field inside the liquid core of the bloom cannot be measured at the caster, the velocity at the mould level can be measured by submerging a nail into the liquid steel flow. The skull forming at the tip of the nail is directly linked to the occurring surface velocities. These measurements can then be compared with numeric simulations of the nail dipping. They are restricted to the upper part of the strand but also take the cut off part (velocity field, stirring forces ...) into account.
This work is a first attempt to simulate the nail dipping process and thereby bridging the gap between plant measurements and simulations of the continuous casting with mould-electromagnetic stirring. The sensitivity of the simulation results to different parameters (nail position, stirring forces ...) will be investigated and the results compared to simulations of a round bloom caster with M-EMS.