Numerical Simulation Of The Influence Of Electromagnetic Field On Electroslag Remelting

Electroslag remelting technology has considerable advantages in reducing segregation,improving the purity of steel,reducing sulfur content,increasing crystal density,and reducing non-metallic inclusions.However,due to the unreasonable cable layout in the actual production activities,the electromagnetic field is not uniform,which causes the melt flow in the slag bath to be uneven and the temperature field to be uneven,ultimately making the surface quality of the ingots uneven.Based on the actual production process,the finite element method was used in this paper to establish multiple models,and short-circuit loops were introduced innovatively.The ANS YS and FLUENT softwares were used to perform multi-field coupling simulations including electromagnetic,flow,and temperature fields for the traditional electroslag remelting process and the rapid electroslag remelting process using conductive molds.The simulation results and experimental results were compared to verify the accuracy of the simulation results.The main conclusions are as follows:(1)The distributions of current density of the traditional electric slag actual model,traditional simplified model,and coaxial conductive model calculated using the finite element method were relatively symmetrical.Due to the deflection effect of the shortcircuit loop on the magnetic field,the electromagnetic force inside the short net in the slag pool and ingot is greater than that outside.The slag in the slag pool of the traditional practical model flows from the lower part of the electrode near the short net side to the side wall of the slag pool along the short net plane,and then returns along the side walls of both sides,resulting in the uneven distribution of the temperature field in the traditional practical model,the shape of th molten steel pool changes,and the bottom of the molten slag pool shifts to the outside of the short net.The traditional electroslag coaxial conductive model could constrain the electromagnetic field and make the electromagnetic field in the slag pool and ingot symmetrical with the central axis,so that the electromagnetic force in the slag pool and the molten steel was symmetrical,and the flow field and temperature field were also symmetrical so as to solve the problems of temperature field deviation and the shape change of the molten steel pool.(2)The current flow direction in the three models of ESR was divided into two directions:electrode-side of slag pool and electrode-steel liquid,so the distribution of the compound field was also different.The existence of the conductive mold circuit wire weakened the electromagnetic field near the wire side in the slag pool and ingot,so two minimum areas of the electromagnetic field appearred in the ESRR actual model,the electromagnetic force in the minimum area of the slag pool near the short net side is larger than the far short net side.The direction of electromagnetic force in some areas of the molten steel is the same as that out of short-circuit loop circle.The deviation of the electromagnetic force resulted in the deviation of the flow field and the temperature field in the high temperature zone,which made the heat transferred from the slag pool to the molten steel uneven,and the bottom of the molten steel pool moved far away from the short-circuit loop circle.(3)The ESRR coaxial conducting method could restrain the electromagnetic field in the molten steel and slag pool and protect it from the interference of the stray electromagnetic field produced by the short-circuit loop.The magnetic flux density in the molten steel and slag pool was symmetrical and larger than that in the simplified model.The electromagnetic force was symmetrical in the central axis so that the flow field was symmetrical and not biased.Then the temperature field was symmetrical,forming a "V"shape of molten steel pool about the symmetry of the central axis.Because the current flew out through the conductive crystallizer partly,the shapes of all molten steel pools calculated by ESRR model were shallower than the ESR models.(4)The experimental results of electromagnetic field measured by traditional electroslag remelting experiment show that the electromagnetic induction intensity values of the three measuring points of ?=0°,90° and 270° are close to the field measurement values,and the deviation of the measuring point of ?=180° is slightly larger but within the acceptable range.The results indicated that the traditional electroslag remelting models established in this chapter were relatively accurate and could predict the multi physics field in the electroslag remelting system.(5)The results of sulfur imprint test showed that the actual model of ESR was in good agreement with the sulfur imprint test results in the range of x<-50 mm,which was slightly larger than the experimental result in the depth of the molten steel pool,and slightly lower than the experimental result in the side wall of the molten steel pool in the positive x direction.The distance between the bottom of the molten steel pool and the central axis was the same.The simulation results of the practical model of ESRR were in good agreement with those of sulfur imprint experiment,which showed that the simulation results were accurate.