Mold Experimental Research On Flow And Behavior Of Slag-Metal Interfacial In Slab Mold With Swirling Flow

In continuous casting process of steel,the uneven outlet flow from submerged entry nozzle(SEN)leads to uneven distribution of the flow field and temperature field and the larger meniscus fluctuation in the mold and so on.It influences the surface and internal quality of the billet as well as the casting speed.The swirling flow in SEN is effective to control the occurrence of the uneven outlet flow.A technology that set up a mechanical swirling blade in SEN for swirling flow has been extended to industrial applications.At present,the behavior of the slag-metal interfacial with swirling flow has not been reported.The behavior of slag-metal interfacial is of vital importance for the quality of billet.So the research of the slag-metal interfacial behavior has great significance for the optimization and promotion of the process.In this paper,water model experiment for mechanical swirling flow was carried out based on the prototype slab continuous casting machine of a steel company.In this paper,the effects of different process parameters(argon flow rate,SEN immersion depth,with or without swirling flow,structure of SEN)on the flow field and the slag-metal interfacial behavior in slab mold were studied.The flow field in mold was investigated by tracer and video camera.Using silicon oil to simulate the slag,the behavior of slag at the interface was investigated by video camera.The two-dimensional velocity distribution was acquired by ultrasonic Doppler velocimetry(UDV).We get the following main conclusions:1.With swirling flow,in order to make the SEN outlet flow not impact directly on the wideface of the mold,the nozzle should be rotated to a certain angle round its vertical axis,the angle(4°-12°)increases with the increase of the casting speed(0.31m/min-1.13m/min)in this study;with the increase of argon flow rate(0.85L/min-2.0L/min),the angle decreases firstly and then increases.2.SEN immersion depth(50mm-100mm)and casting speed(0.31m/min-1.13m/min)have little effect on the angle between the flow discharged from the two outlet of the nozzle,the larger casting speed enhances the mixing of the flow in mold.3.Argon blowing make the velocity of the slag-metal interface faster,the interface become disordered;argon blowing make the slag foaming,so as to increase the thickness of liquid slag and the thickness of slag inhomogeneity increases,this may increase the probability of entrapment.4.With the decreases of the immersion depth,the flow velocity of the slag-metal interface increases,the inhomogeneity of the slag is uneven.5.In the case of with swirling flow,the velocity of the slag-metal interface is smaller and the thickness of slag distribution is more uniform.6.The effect of structure of SEN on the slag-metal interfacial behavior:in the case of without swirling flow,the slag-metal interfacial behavior is mainly affected by the bottom shape of nozzle without swirling,the concave bottom nozzle make the distribution of liquid surface slag more uniform;in the case of with swirling flow,the slag-metal interfacial behavior is mainly affected by the optimized structure of outlet edge of the nozzle,the optimized structure of outlet edge of nozzle makes the distribution of interfaceface slag more uniform.