Numerical Simulation Of Distribution System In Molten Pool Of Twin Roll Strip Continuous Casting

Twin roll strip continuous casting is a process that combines metal solidification with rolling.The strip products produced by this technology have the advantages o f good quality and easy cutting.At present,the width of thin belt section is too narrow to meet the needs of industrial development.When the width of the strip increases,how to distribute the molten steel evenly to the molten pool becomes one of the problems that need to be solved urgently.The distribution system of twin roll high-speed cast steel molten pool plays a decisive role in whether the molten pool level is stable and even,which directly affects the strip quality and process flow,and is the core problem to be solved in twin roll casting and rolling process.There are many factors that affect the flow distribution in the molten pool.Designing a reasonable distribution system is one of the effective methods to improve the uniformity of the flow distribution in the molte n pool.In this paper,Φ 800 × 1800 mm vertical twin roll strip continuous casting molte n pool as the research object,a set of three-dimensional mathematical simulation model for coupling calculation of molten steel flow field and temperature field in the molte n pool is established.The flow behavior and temperature distribution of molten steel in the molten pool are studied by using mathematical simulation method,and a reasonable distribution system is designed and optimized.On this basis,the process parameters are studied for the distribution and solidification of molten steel temperature field in the molten pool The influence law of heat transfer process.The main contents of this paper are as follows:The evaluation method of molten steel flow and temperature uniformity in molte n pool is studied and put forward.The distribution uniformity of molten steel in the molten pool can be judged by several indexes,suc h as the velocity uniformity of free liquid level in the molten pool,the renewal of steel liquid level in the upper part of the molten pool,the fluctuation characteristics of liquid level and the uniformity of temperature field.The distribution mode of distributor + distributor is adopted in the distribution of molten pool flow.Different distributor structures are designed to study the influence of side hole length and inclination angle on the flow uniformity of molten pool.The results show that when the side hole length of bifurcated distributor is 180 mm and the inclination angle of side hole is-10 °,the flow of molten steel in molten pool is more uniform.Different structures of the distributor are designed to study the influence of the length of the distributor,the number of side holes,the wedge angle of the bottom of the distributor and the arrangement of side holes on the distribution uniformity of the molten pool.When the length of the distributor is 1550 mm,the number of side holes is13,the inclination angle of the bottom of the distributor is 60 ° and the arrangement of side holes is M-shape,the molten steel flow in the molten pool is relatively uniform.On this basis,the area and inclination of the side hole of the distributor are adjus ted and optimized to obtain a more uniform flow pattern of molten steel in the molten pool.The effects of casting speed,roll gap thickness,bath depth and distributor immersion depth on the flow field,temperature field and solidification process of molten steel in the bath of twin roll strip casting were studied by mathematical simulation.The results show that the increase of casting speed is beneficial to the uniform distribution of molten pool level and outlet temperature;the increase of roll gap thickness increases the uniformity of molten pool outlet temperature;the increase of molten pool depth increases the residence time of molten steel in the molten pool,which will lead to the increase of liquid temperature difference;the increase of the imme rsion depth of the distributor from 60 mm to 90 mm decreases the uniformity of outlet temperature.When the casting speed and the thickness of the roll gap increase,the solidification end point will move down and toward the outlet of the molten pool;when the depth of the molten pool and the immersion depth of the distributor increase,the solidification end point will move up.