| The mold is the key part of the continuous caster, in which the metallurgical processes are very critical to improvement of slab quality. A lot of researches showed that most of the defects affecting steel quality in the process were closely associated with fluid flow in the mold. With increase of casting speed, both of the flow rate and flux of the flow discharged in the submerged entry nozzle (SEN) increased and the flow of liquid steel was accelerated in the mold, Moreover, the flow stability of liquid steel was deteriorated. Excessive surface velocity could entrain mold flux and cause surface level variations and fluctuations that produced surface defects. Excessive velocity of liquid steel could strengthen scouring action to the initial solidification shell, degraded the uniformity of the shell, increased the depth of the mark and deep penetration of the jet entering the mold and hindered the inclusions and bubbles float upward that produce the inter defects. Accordingly it is extremely important to study and control the flow in the mold. To solve these problems, electromagnetic techniques have been developed and applied to the continuous casting process, such as electromagnetic brake and electromagnetic stirring. In the paper, the flows in mold of the continuous casting slab, billet and two- roll strip with electromagnetic fields have been studied, and the effects of the flows on the quality of steel have been analyzed combined with the questions in the industry. The different electromagnetic fields have been applied to improving the flows in three kinds of molds according to their flow characteristics. The main studies are given as follows.For the high slab continuous casting, mercury was used to simulate the flow liquid steel with electromagnetic brake ruler (EMBR) and Flow Control Mold (FC-Mold), which are widely used in the industry at present. The flow in the mold and fluctuation of meniscus were measured by the DOP2000 velocimeter. The effects of magnetic fields on the flow in the mold have been analyzed. In addition, the effects of magnetic flux density and location of the magnets on the flow in the mold have been studied as well. The results showed that the flow discharged from the SEN was suppressed, both of the distribution of the kinetic energy and the turbulence intensity were changed, and the flow stability of liquid metal in the mold was enhanced. In electromagnetic brake ruler when Bmax was more than 0.29T, the surface level fluctuations were weakened, the flow at the meniscus became stable and the flow at the meniscus were improved, and at the same time the impact action of liquid metal was weakened, and the penetration depth was reduced. The Bp=0.16T in the prototype is corresponding to Bmax=0.29T in the model. So in the industry when the Bmax is more than 0.16T, it is beneficial to optimize and control the flow in the mold and improve the quality of steel. It was beneficial to improve the flow in the upper eddy, fluctuation of meniscus and stability of the flow when the magnet was located near the SEN. However, it was good to reduce the impact action and penetration depth when the magnet was far from the SEN. Hence improvement of the flow relies on many factors, e.g., continuous casting process and equipments in the industry. Compared with EMBR, it was more effective to use FC-Mold for improving the flow in the upper eddy, fluctuation of meniscus and stability of the flow. Nevertheless, it was more effective to reducing the impact action and penetration depth in the lower mold using EMBR. The experiment results showed that a magnetic field could not only damp flow, but also change the flow direction and distribute the flux of liquid steel. Thus, the flow in the mold could be improved by optimizing the distribution of magnetic field.For billet continuous casting, the electromagnetic swirling nozzle has been exploited on the base of straight nozzle. The physical and numerical modeling has been carried out to study the flow patterns in continuous casting billet mold using swirling flow nozzle, and the effect of electromagnetic stirring in SEN was simulated by setting a swirl blade in SEN. The results indicated that the swirling flow nozzle technique is conducive to improve the flow field in the mold, enhance the flow in the upper mold, and increase the velocity on the free surface. The activity of liquid level and the effectiveness of molten slag increased. The flow was weakened in the lower mold and the penetration depth was effectively reduced. The flow in the horizontal section became uniform. The turbulent intensity in upper mold increased and reversely the turbulent intensity in the lower mold was reduced, so it was beneficial to improve the temperature distribution in the upper mold and promote the float of inclusions and bubbles in the lower mold. When the blade was near the outlet of nozzle, the penetration depth was reduced and the flow on the free surface was enhanced. Thus, the effect is more obvious when the electromagnetic stirrer is more closely near the outlet of the nozzle theoretically, but its location should be determined according to the continuous casting process, equipments and operation parameters in the industry. The experiment results of low melting point alloys showed that the swirling flow in the SEN could be generated by the electromagnetic stirrer. Investigation of the angle of the blade showed that the tangential velocity did not increase any more when the angle of the blade was less than a certain value; the scour action to the inner wall of the nozzle was enhanced by the swirling flow. The dimensionless swirling number showed that the effect of swirling number on penetration depth was not obvious by increasing swirling number when swirling number was more than 0.5. In the case of electromagnetic stirring, the intensity of electromagnetic stirring determined the tangential velocity and swirling number at the outlet of the nozzle, and there was the optimization intensity of electromagnetic stirring. Consequently, the intensity of electromagnetic stirring should be determined according to operation parameters in continuous casting, e.g., casting speed, in the industry.For two roll strip casting, the flow in twin roll pool was controlled by imposing static magnetic fields coupled with direct current in the nozzle. The effects of location of magnets and intensity of electric currents on surface fluctuation and flow behaviors near the meniscus have been investigated using mercury, respectively. The experimental results showed that it was beneficial for improvement of the flow at the meniscus and the free surface fluctuation to apply the nozzle electromagnetic brake technology, which would be good for improvement of the conditions of initial solidification and the quality of steel. Additionally, it could provide good conditions for other technologies. When the magnet was placed nearer the outlet of the nozzle, it is beneficial to reduce the free surface fluctuation. The magnetic field coupled with direct current is more effective for suppression of the flow near the meniscus and the free surface fluctuation in twin-roll strip casting caster compared with only imposing a magnetic field.
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