| The tundish plays an important role in the modern iron and steel smelting process.The tundish is the last metallurgical vessel of molten steel.At this stage,it is necessary to promote the removal of inclusions as much as possible.The tundish is also the initial step of the continuous casting stage.Parameters such as the temperature of the molten steel composition should be used to ensure the stability of the product.It can be seen that the metallurgical effect of the tundish has a greater positive impact on the smelting of high-quality steel products.The flow control characteristics in the tundish play a decisive role in the metallurgical effect of the tundish.In this paper,the influence of turbulence inhibitor and retaining wall on the flow control characteristics of an eight-strand billet tundish in a steel company is investigated by means of numerical simulation and field industrial production test,and the optimal flow control scheme combination is optimized.The conclusions are as follows:(1)According to the results of numerical simulation,the turbulence inhibitor can buffer the molten steel injected from the long nozzle of the ladle and reduce the kinetic energy;optimizing the retaining wall can make the molten steel stream have better flow characteristics.For the studied eight-strand billet tundish,the steady-flow effect of the eaves turbulence inhibitor is better than that of the eaves-free turbulence inhibitor,that is,the turbulence inhibitor A has a better flow control effect;the optimized four-hole retaining walls are better than the Use retaining wall,and retaining wall scheme C has the best effect.(2)For the studied eight-strand billet tundish,the optimal flow control combination scheme is scheme 4,that is,the "flow barrier C+turbulence inhibitor A" flow control combination scheme.The flow field distribution of this scheme is reasonable to avoid the molten steel stream from disturbing the pouring surface and directly washing the refractory material.The RTD curve and data show that in all the schemes,the ratio of the piston zone to the dead zone is the largest,and the overall standard deviation of each stream is small.The consistency is better;meanwhile,the temperature field is evenly distributed and the temperature gradient is small.(3)According to the comparison of industrial test and bottom-up survey data,it is known that the product quality under the optimized tundish flow control scheme is better.The optimized tundish flow control scheme can significantly reduce the oxygen and nitrogen content in the slab.The total oxygen content and nitrogen content in the 42CrMo steel grade industrial test have been reduced by 4.30 × 10-6 and 17.85 × 10-6.Respectively,compared with the bottom survey samples,and the reduction rates have reached 20%and 28%;The total oxygen content and nitrogen content of the 20CrMnTi steel grades were reduced by 6.97 ×10-6 and 14.50 ×10-6,respectively,and the reductions reached 40%and 24%.The optimized tundish flow control scheme can significantly reduce the number density of inclusions in the slab.The total number density of the 42CrMo and 20CrMnTi steel grades have decreased by 35%and 38%,especially for large-size inclusions.The optimized tundish flow control scheme can significantly improve the inclusion qualification rate of the final rolled product.The fine system and qualification rate are increased by 26.6%,the fine system and qualification rate are increased by 2.34%,and the Ds category qualification rate is increased by 2.60%,and the pass rate increased by 26.08%.Through the research on the flow control technology of tundish,the metallurgical function of tundish is brought into full play,which provides a theoretical basis for field production. |
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