Study On Metallurgical Behavior Of Non-reactive Mold Fluxes Under Electromagnetic Field

Non-reactive mold flux is a kind of Ca O-Al₂O₃ based mold flux,which uses Al₂O₃ instead of Si O₂ in traditional mold flux.It is mainly used in High aluminum and manganese steel continuous casting production.At present,electromagnetic technology is widely used in continuous casting process.In the process of electromagnetic continuous casting of high aluminum and high manganese steel,the mold flux presents ionic structure at high temperature and has certain conductivity.Under the electromagnetic field,it is bound to be affected by the force effect,magnetic energy effect and thermal effect of the magnetic field,resulting in the change of its high temperature structure and physical and chemical properties,which affects the smooth process of continuous casting.Therefore,it is the key to master the metallurgical behavior of non-reactive mold flux in electromagnetic continuous casting of High aluminum and manganese steel.The metallurgical properties of non-reactive mold flux under high frequency magnetic field were studied by using magnetic field application method,slag column deformation method,rotary viscometer and infrared emission device.The results show that the melting temperature,melting range,viscosity and transition temperature of non-reactive mold flux increase with the increase of magnetic field strength in the range of 80?120 m T,and the heat flux first decreases and then increases with the increase of magnetic field strength.Based on the mathematical model of magnetic field distribution,combined with the mathematical model of meniscus shape,flow field,solidification heat transfer and lubrication under magnetic field,the mathematical model of metallurgical behavior of mold flux in mold under high frequency magnetic field was established.The results show that the root cause of uneven distribution of magnetic field in the mold is the reflection effect of copper wall in the slit on the magnetic field;the slit should be designed to be narrow in the bottom and wide in the top,with the length of180?200 mm and the width of 0.8?1.0 mm,and more slits should be opened.The frequency of magnetic field should be kept at 20?30 k Hz.Reasonable liquid level should be controlled as far as possible in the center or up position of coil.The metallurgical behavior of non-reactive mold flux in high frequency magnetic field was studied by using the mathematical model of metallurgical behavior of mold flux in mold.The results show that the meniscus widens the slag channel under the electromagnetic force,and the molten steel reduces the erosion to the shell and increases the erosion to the nozzle under the electromagnetic force,which is conducive to the smooth inflow of liquid slag.The excessive electromagnetic force in the three-phase region at the bottom of the meniscus results in the shift or eddy current of the liquid slag at the meniscus.Under the electromagnetic force,the up and down"double vortex"flow field is formed in the slag pool,which has a good stirring effect on the slag pool.Under the action of electromagnetic force,the slab temperature in the refluxing zone decreases and the shell thickness increases.Under the action of Joule heat,the cold and hot surface temperatures of copper plate increase.Under high frequency magnetic field,the peak value of heat flux in slag film increases by 60.8%,the thickness of liquid slag increases by 29.0%,the peak value of dynamic pressure in slag channel increases by 34.9%,the maximum differential pressure increases by 23.5%,the peak value of slag consumption increases by 28.4%,and the peak value of liquid slag friction decreases by 7.6%.Figure 67;Table 4;Reference 137.