Numerical Simulation Study On The Movement Behavior Of The Slag-Steel Interface In The Mold Under The Condition Of Argon Blowing

In the process of injecting molten steel from the tundish into the mold,the inclusions such as Al2O3 and SiO2 in the molten steel are likely to accumulate and nod on the nozzle wall of the mold,causing the nozzle to block and bring great harm to the quality of the cast slab.In order to suppress the clogging of the immersion nozzle of the mold,the nozzle argon blowing technology came into being.The nozzle argon blowing technology introduces argon bubbles into the molten steel.The aggregation and fragmentation of the argon bubbles will change their size and spatial distribution,thereby changing the flow field of the molten steel and the movement behavior of the slag-steel interface.In order to study the interaction of bubbles in molten steel and the movement behavior of the slag-steel interface under the condition of argon blowing,this paper establishes a method that considers the polymerization and breaking of argon bubbles in the mold,the movement of the slag-steel interface,the movement of the slaggas interface,the bubbles and the molten steel.Multi-scale mathematical model of interaction.The multiphase flow model used by the predecessors did not comprehensively consider these factors.In addition,traditional research assumes that the size of a single bubble in the mold,but in fact,inside the nozzle,outlet and other parts of the mold,the bubbles will collide and aggregate and break.For example,large bubbles will preferentially float up from the vicinity of the nozzle and impact the slag-steel interface.Slag eyes are formed,causing secondary oxidation of molten steel.In this study,the multi-size distribution of bubbles and the movement behavior of the slag-steel interface caused by them are simulated.The main contents and conclusions of this article are as follows:(1)Under the condition of argon blowing,the increase of the casting speed increases the interface wave height near the narrow surface of the mold,and the interface velocity increases,while the interface wave height near the nozzle gradually decreases,and the interface velocity decreases;the increase of the argon blowing volume makes the inside of the mold,the wave height of the slag-steel interface increases,and the interface velocity increases,among which the influence on the vicinity of the nozzle is significant,and the effect on the narrow surface is not obvious;the increase of the thickness of the slag layer increases the overall interface wave height,and the interface velocity decreases,which is the highest point of the slag-steel interface Near the nozzle,the maximum interface velocity is near the narrow surface.(2)Under the condition of argon blowing,the slag eye on the top surface of the mold mainly consists of two positions:1)near the immersion nozzle;2)near the narrow surface.The simulation found that the slag eye on the top surface of the mold changes transiently and is asymmetric about the center line of the nozzle.(3)Under the condition of argon blowing,with the increase of the casting speed,the narrow surface area of the slag eye on the top surface of the mold increases,the area of the slag eye near the nozzle continues to decrease,and the total area of the slag eye increases;with the increase of the amount of argon blowing,the slag eye area of the narrow surface on the top surface of the mold decreases,and the slag eye area near the nozzle continues to increase,and the total area of the slag eye increases;with the increase of the initial slag layer thickness on the top surface of the mold,the slag eye area near the narrow surface continues to decrease Until it disappears,the area of the slag eye near the nozzle continues to decrease,and the total area of the slag eye continues to decrease.Taking the smallest slag eye area as the standard,under the simulated conditions,the best process parameters are:casting speed 0.6 m/min,argon blowing volume 0.5 L/min,slag layer thickness 15 mm.(4)Under the condition of argon blowing,the increase in the casting speed increases the impact depth and distribution range of the bubbles,and the size of the bubbles decreases;the amount of argon blowing increases the bubble volume fraction,the bubble size increases,and the bubble distribution becomes wider;the influence of the thickness of the slag layer is not obvious.