Numerical Simulation Study On The Twin-roll Casting Process Of Silicon Steel Strip

Twin roll strip casting process is one of the frontier technology in the field of metallurgy in which the molten steel is fed through a delivery system into the mold, which is formed by the two-counter rotating water-cooled rolls and two side dams. The molten steel is solidified in a few seconds and exits out from the rolls, and then machined into finished or semi-manufactured products. Compared with traditional steel production process, it has the advantages of simple process, less investment and low energy consumption. However, surface cracks often initiate in the strip produced by twin-roll casting, which is seriously affecting the quality of the production. We can analyze fluid flow, heat transfer and solidification of different process parameters and delivery systems, and provide theoretical guidance to determine the experimental parameters by numerical simulation.In this paper, a three-dimensional coupled model was developed which has been proved by the experiment. The casting process of different casting parameters and delivery systems can be researched by the model. The casting speeds are 0.5 m/s,1.0 m/s and 1.5 m/s and the casting temperatures are 1780 K,1800 K and 1820 K respectively. The immersion depths of the metal delivery systems are 35 mm,45 mm and 55mm while the angles of the water gaps are 10°,20° and 30°. The controlling variables method is used for investigate the influence on the flow field, temperature field, the fluctuation of the liquid level and the impact on the side dam by different parameters.The calculated result shows that the influences are caused by different parameters on the molten pool. There are two vortexes formed in the molten pool, which can increase the efficiency of heat conduction of the melt and helps not only with dendrite fusing and refining grain, but also reducing the segregation. The temperature of the strip at the exit increased with increasing casting speed and casting temperature while the location of the solidification point moves downwards as well. The strip had not been solidified until the exit when the casting speed or the casting temperature is too high, and the freezing point position of the molten steel located far above the exit when the casting speed or the casting temperature is too low. The casting speed has a great influence on the fluctuation of the liquid level and the impact on the side dam, while the casting temperature only impacts on the side dam and has little influence on the liquid level. The temperature of the strip at the exit decreased with the increasing immersion depth, while the angle of the water gap has little influence. The fluctuation of the liquid level, the location of the vortexes and the impact on the side dam are changed with the change of the immersion depth and the angle of the water gap. According to the analyze of the fluid flow, heat transfer and solidification, we can optimize the parameters in order to improve the quality of the silicon steel strip. Computational analysis reveals that, the finest experiment parameters are 1.Om/s for rolling speed,1800K for casting temperature, 45mm for water immerse depth and 20° for water gap angle.