Experimental Study On Metal Liquid Level Behavior In Mold Under Magnetic Constraint

In the process of continuous casting,the deformation and fluctuation of liquid surface in the mold have an important influence on the production process and the quality of billet.Deformation and fluctuation of liquid surface in the mold are too large will lead to slag entrapment and molten steel reoxidation.Deformation and fluctuation of liquid surface in the mold are too small will adverse to the mass and heat transfer between slag and molten steel.Therefore,the control of metal liquid surface behavior in mold is significant.Because of the force effect of the electromagnetic field on the liquid metal,electromagnetic force can constrain and control the liquid metal,so the electromagnetic technology can be applied to the controlling of the metal liquid surface behavior in mold.A new method is put forward using the effect of magnetic constraint to control the behavior of metal liquid surface in mold.it means that a horizontal alternating magnetic field is placed above the mold,and a vertically downward magnetic pressure on the liquid surface can be produced due to the electromagnetic induction.As a result,it can achieve the controlling of liquid surface.In order to improve the efficiency of the magnetic field generator,three kinds of magnetic field generators is designed by different winding ways:vertical square coils,gradient square coils,planiform square coils.Through the simulation calculation,it is found that the distribution of horizontal magnetic field below the working area of the three coils has the same trend,but the magnetic flux density is different.The role of the magnetic on the molten steel due to the skin effect of high-frequency magnetic field exists only in the skin layer of metal liquid surface.The order of the magnetic field strength and induced electromagnetic force of three coils is planiform square coils>gradient square coils>vertical square coils.There are extra horizontal induced electromagnetic force of planiform square coils on metal liquid in narrow edge of mold,in order to avoid this influence,gradient square coils is selected as magnetic field generator in the experiment.The influence of process parameters(casting speed,submerged depth of SEN,outlet angle of SEN,mold width)on the liquid surface behavior in the mold,the liquid surface behavior in the mold under magnetic constraint,and the influence of process parameters on the magnetic constraint effect are consideredThe experimental results show that the deformation and fluctuation of liquid surface in the mold have a direct relationship with casting speed,submerged depth of SEN and outlet angle of SEN.With the increase of casting speed,the decrease of submerged depth and downward outlet angle of SEN,the deformation and fluctuation of liquid surface increase in varying degrees.With the increase of mold width,the fluctuation of liquid surface increases.Applying the magnetic constraint,when the edge of coils working area is placed aligning the narrow edge of mold,the effect of restraining the deformation of liquid surface is better than when the edge of coils working area is placed aligning the narrow edge of mold.With the increase of the current intensity,the deformation and the fluctuation of the liquid surface decrease first and then increase.Therefore,there is a suitable current intensity which will let the liquid surface have a better deformation,and there is a suitable current intensity which will let the liquid surface have the smallest fluctuation.The effect of magnetic constraint on the liquid surface under different process parameters is different.With the increase of casting speed,the decrease of submerged depth and downward outlet angle of SEN,the effect of restraining the deformation of liquid surface under magnetic constraint will be more clearly,and the current intensity for a better deformation of liquid surface will be lager.Magnetic constraint can be applied to the condition of larger casting speed or smaller submerged depth of SEN or smaller downward outlet angle of SEN,and we can obtain both the production advantages of these conditions and a better liquid surface deformation.With the increase of casting speed,the effect of restraining the fluctuation of liquid surface under magnetic constraint will be more clearly,and the current intensity for the smallest fluctuation of liquid surface will become lager.