| Electromagnetic metallurgy technology is a process,control process and preparation of new materials in which various types of electromagnetic fields strengthen metallurgical reactions through their electric,magnetic,thermal,force and other effects.For slab continuous casting process,the electromagnetic stirring technology of slab mold can promote the floating of bubbles and inclusions in liquid steel,uniform the composition of liquid steel,reduce the temperature gradient in the mold,so as to improve the quality of slab.In this thesis,the multi-mode electromagnetic stirring technology of traveling wave magnetic field is adopted,and the electromagnetic deceleration mode is selected to control the outflow of liquid steel from the side hole.In this thesis,the continuous casting thick slab with cross-section size of1600mm×350mm was taken as the research object,and the electromagnetic field model of slab mold was established by using ANSYS Maxwell finite element analysis software to solve and analyze the distribution characteristics of magnetic field and electromagnetic force under electromagnetic deceleration mode.The results show that the magnetic field directions on both sides of the mold are consistent,perpendicular to the billet,and change with the change of phase Angle.The magnetic induction intensity is mainly distributed on the surface of the billet where the electromagnetic current controller is installed,and the magnetic induction intensity is small in the billet or away from the installation position.The direction of the time-average electromagnetic force is directed downward from the narrow plane towards the water mouth.The magnitude of the electromagnetic force is mainly determined by the current intensity.The larger the current intensity is,the larger the electromagnetic force will be,and the optimal electromagnetic frequency is determined to be 7Hz.The three-dimensional coupling model of flow,heat transfer and solidification of molten steel in slab mold was established by using Fluent software.The low Reynolds number turbulence model and solidification and melting model were adopted to solve the problem by using PISO algorithm.The distribution characteristics of flow field and temperature field of molten steel in the mold with the change of drawing speed and the formation of billet shell at the mold outlet were studied.The results show that with the increase of drawing speed,the flow rate of liquid steel in the mold increases,the temperature gradient also increases,and the average temperature of mold billet cross section increases.The shape characteristics of the blank shell at the outlet of the mold are basically the same,the blank shell is thick in the middle of the wide surface and thin in the corner.When the drawing speed is 0.7m/min,0.8m/min,0.9m/min and 1.0m/min respectively,the blank shell thickness at the center of the narrow surface at the outlet is17 mm,14mm,8.7mm and 8.5mm,respectively.Therefore,it can be determined that the casting speed should not exceed 0.8m/minThe profile module in Fluent was used to read the generated electromagnetic force file,and the electromagnetic force was taken as the source term to carry out coupling calculation with the flow field and the temperature field,so as to analyze the flow of liquid steel in the mold and the formation law of the billet shell under the action of magnetic field.The effects of different current intensities on the flow,heat transfer and solidification behavior of molten steel at a drawing speed of 0.8m/min were studied.The results show that with the increase of the current intensity in the electromagnetic deceleration mode,the impact velocity of the molten steel from the side hole to the narrow edge decreases gradually,the temperature distribution in the mold is more uniform,and the temperature gradient of the cross section of the billet decreases.The thickness of the blank shell at the mold outlet is more uniform.When the current intensity is 200 A,250A,300 A and 350 A,the thickness of the blank shell formed in the center of the narrow surface is 15 mm,17.5mm,22 mm and 19.5mm,respectively.According to the thickness of the narrow blank shell,the optimal current intensity is determined to be 300 A. |
PDF Full Text Request