Effect ofloulse magnetic field on two-phase zone of

IntroductionNevertheless diversity and multiplicity of electromagnetic systems for stirring by continuous casting of steels that appeared during 50-years of previous century thanks to S. Junghans and O. Shaaber, the conventional stirring systems for billet/bloom casting that are in operation by numerous users, are uniform, extreme simple, reliable metallurgical installation that should based on the next scientific-technical principles:1. In-mold stirrer does not make the obstacles for workability of mold; 2. The copper mold has to be simple and cheap, like mono-block, easy changeable; 3. For decreasing of magnetic flux leakage the magnetic system of stirrer has to be submerged into cooling water, being located as close to copper mold as possible;4. The main intention of in-mold stirrer is taking away of melt superheat and the stirrer has to provide efficient heat transfer through interface solidus-liquidus;5. The revolving magneto-hydrodynamic flow in the mold is a preferable for reaching of high heat transfer on the interface and uniform freezing of ingot on the mold surface.The aim of this publication is to show the new manner of electromagnetic in-mold stirring that allows to satisfy the above-mentioned requirements, following the principle of minimum changes in conventional, very rational caster. As example of the in-mold electromagnetic asynchronous stirrer in-mold stirrer for bloom caster 300ϫ400 mm was taken in consideration. The mathematical two-and three-dimensional models of turbulent magneto-hydrodynamic flows (ANSYS software) and experimental data were used for analysis of methods of electromagnetic stirrer improvement. The schematic view of in-mold electromagnetic stirrer model is shown in the Fig. 1. Meniscus DisturbanceAnalyzing the situation with meniscus disturbance, which causes the lowering of surface quality and nonmetallic inclusions entrapping, let's take in consideration only methods and equipment, which have found a place in wide casting practice: rotational asynchronous low frequency stirrer that is fed from multi-phase inverter. We avoid a numerous suggestions of electromagnetic molds such as mag- ISIJ International, Vol. 44 (2004) The elaboration relates to a method of electromagnetic stirring in continuous casting of carbon steels, when the surface quality and entrapping of nonmetallic inclusions still remain as the major problems concerning of ingot quality and success on the steel market.The improvement of surface quality of ingot means a decreasing or elimination of oscillating mark, corner cracking, and pinholes. Intensity of nonmetallic particles entrapping depends on meniscus disturbance: inclusions do not penetrate into liquid portion of ingot through quiet meniscus. Based on the phenomenon of electromagnetic edge effect, which exists in each of asynchronous stirrer, by condition of feeding of magnetic system by polyharmonic currents the new method of in-mold electromagnetic stirring has been developed. Thanks to that the depth of oscillating marks decreases, the flow on the m...

No abstract

No abstract

No abstract