Physical Simulation Of Molten Steel Flow Behavior In High Speed Billet Continuous Casting Mold

High-speed continuous casting is an important direction for today’s billet continuous casting technology.By increasing the speed of casting,it not only achieves the purpose of reducing flow and increasing efficiency,but also it is the technical basis for the realization of billet continuous casting and rolling and endless rolling.The flow behavior of the molten steel in the continuous casting mold is the key to whether the high-speed continuous casting of the small billet can run forward and affect the quality.At present,the flow of molten steel in the high-speed billet continuous casting mold is at home and abroad.Physical simulation studies of behavior have not been involved.Therefore,it is of great significance to study the flow behavior of molten steel in a high-speed billet continuous casting mold.In this paper,the 160×160mm×mm section billet continuous casting mold of a steel plant production test is used as a prototype,and a 1:1 hydraulic model is designed based on the similar principle.The physical simulation method is used to study the drawing speed of 3.0 to 6.5m/min.Billet continuous casting mold flow behavior under different process conditions.In addition,this study also refined the current physical simulation model,designed a shell model based on the growth law of the shell,and conducted a comparative study.During the experimental study,the effects of the Submerged Entry Nozzle(SEN)inner diameter,the SEN inserting depth,and the casting speed on the distribution of the liquid slag in the mold,the fluctuation of the liquid level,the depth of impact,and the flow field were analyzed.The parameters of SEN inner diameter and insertion depth were optimized respectively in speeds ranging from 3.0 to 4.5 m/min and 5.0 to 6.5 m/min.Finally,a set of SEN parameters and insertion depth parameters for different casting speed ranges were obtained.Through a large number of water model experiments and comprehensive analysis,the results show that as the casting speed increases,the time for the upper reflow to reach the mold surface decreases,the activity level of the mold increases,the liquid slag tends to be unevenly covered,even slag entrapment and fluid exposure have occurred,and the fluid impact depth becomes larger.The SEN structure has a great influence on the flow state of the mold.The SEN inner diameter is increased,the flow field is basically the same,the flow stream is thicker,the fluid shock depth is reduced,and the liquid level activity of the mold is basically reduced.The depth of SEN insertion has a certain influence on the flow of the mold.As the depth of insertion increases,the depth of stream impact increases,the liquid level of the mold tends to be calm,and the time for the fluid to reach the liquid level of the mold increases.The optimizing of multiple rounds yielded SEN structural parameters and inserting depth parameters for different speed ranges.The SEN with inner diameter of 40 mm at middle-low casting speeds is reasonable at the insertion depth of 120 mm.The liquid level fluctuation range is 0.49~1.12 mm,the streamer impact depth is 550~580mm,and the inner diameter is medium and high.The SEN of 50 mm is more reasonable in the mold with the insertion depth of 160 mm,the liquid lever fluctuation range is 0.75~1.34 mm,and the impact depth range is 578~610mm.The flow behavior of the mold after the billet was loaded was simulated by water.The influence of multiple SEN insertion depths on the flow of the molten steel in the mold was investigated,and the experimental results without considering the shell were analyzed.The results show that the distribution of the liquid slag and the distribution of the flow field are basically the same before and after the shell is considered.However,after the solidification phenomenon is considered,the fluctuation of the liquid level of the mold is increased and the degree of increase is different.The maximum growth rate is 27%.The solidification and shrinkage process of molten steel has a certain influence on the surface fluctuation of the mold.