Research And Simulation On Electromagnetic Stirring In Continuous Casting Of Round Billet

Modern continuous casting process have using the protection measures of submerged nozzle, protecting slag and inert gas, which made the slab quality being greatly improved. But, until the electromagnetic stirring technique has being used, it is possible to control the slab structure of the organization. Expanding isometric zone of slab, reducing the osteoporosis of slab center, center segregation and shrinkage cavity at center, these were why continuous casting technology electromagnetic stirring widely used in continuous casting production.In this paper, we take the rotary type mold electromagnetic stirrer and solidification ending electromagnetic stirrer in a large steel mills in China as the research object. In platform using ANSYS Workbench and ANSYS Fluent we have established mathematical the model of mold electromagnetic stirring and final electromagnetic stirring. Also, the model has been studied and calculated, revealing the distribution of electromagnetic fields and flow field of steel in the mold and solidification.Under the conditions of Mould Electro Magnetic Stirring (M-EMS), electromagnetic fields rotate about the axis in the same frequency with excitation current and electromagnetic force rotate about the axis in the frequency of twice over excitation current. In the axial direction of the slab, from the steel surface to blender center, magnetic induction and electromagnetic force are increasing. From the center of stirrer to the crystallizer, magnetic induction and electromagnetic force are reduced. With the increase of the intensity of current, the magnetic induction and tangential electromagnetic force are also increased. With the increase of the excitation frequency increases the magnetic flux density is reduced. Tangential electromagnetic force increases with increasing frequency when excitation frequency is in the range of 2Hz to 8Hz. The electromagnetic shear force decreases with the increase of the excitation frequency when the excitation frequency more than 9Hz. As the excitation frequency increases the greater of the flow rate of molten steel when excitation frequency is in the range of 2Hz to 8Hz. With the increasing of current intensity the stirring intensity is greater when current intensity in the range of 200A to 400A. In the cross-section of the agitator, from the center of the slab to slab edges, magnetic induction and electromagnetic force are increase. Electromagnetic force is circumferential distribution. The electromagnetic force and the direction of the magnetic field direction of rotation is the same. The tangential electromagnetic force of slab center is almost zero. From slab center to the slab edge molten steel flow rate is increasing. It achieved the maximum value in the slab edge. When excitation frequency is 8Hz and the intensity of electric current is 400A. Molten steel flow velocity is 0.25m/s. The liquid steel near mold wall flow velocity is almost zero. Because of the tangential electromagnetic force, the direction of the flow of the molten steel is from down turn to tilt to the slab edge. Make the high temperature molten steel from the submerged nozzle impact depth becomes shallow to improve the temperature range. It increasing the radial temperature, meanwhile, reducing the temperature gradient on the front edge of solidified shell, which is good for heat transfer.On the condition of Final Electro Magnetic Stirring (F-EMS), with the increases of excitation frequency the Magnetic induction is small amplitude decrease. With the increase of current intensity the magnetic induction is near linear increase. Magnetic induction intensity in slab solidification front is 900Gs when the intensity of electric current is 600A and excitation frequency is 12Hz. The electromagnetic force in slab solidification front is increasing with excitation frequency increasing when excitation frequency in the range of 9Hz to 12Hz. The electromagnetic force in slab solidification front is decreases with excitation frequency increasing when excitation frequency in the range of 12Hz to 20Hz. When excitation frequency is 12Hz and the intensity of electric current is 600A tangential electromagnetic force achieve the maximum value 630N/m3. The liquid steel in slab solidification front flow velocity increasing with increased excitation frequency when excitation frequency in the range of 9Hz to 12Hz. The liquid steel in slab solidification front flow velocity decreases with increased excitation frequency when excitation frequency in the range of 9Hz to 12Hz. Molten steel tangential velocity achieve the maximum value 0.19m/s when excitation frequency is 12Hz and The intensity of electric current is 600A.