Numerical simulation on flow and reoxidation of molten steel in tundish
CHEN Hongliang1, LIU Zhentong1, ZHOU Qiuyue2, BA Juntao3,4, CHEN Wei1, ZHANG Lifeng5
1. School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China; 2. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 3. School of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China; 4. Cast and Forged Steel Division, China First Heavy Machinery Co., Ltd., Qiqihaer 161042, Heilongjiang, China; 5. School of Mechanical and Material Engineering, North China University of Technology, Beijing 100044, China
Abstract：At present, the reoxidation of molten steel in ingot tundish is still lacking in in-depth research. The molten steel was sampled in the VD refining process and tundish during the actual production of 303 t ingot in a factory. The variation for total oxygen (TO) and total nitrogen (TN) content of molten steel and the composition, quantity and size of inclusions were analyzed. The results show that the TO and TN mass fraction of molten steel in the tundish are increased by 5.59×10-6 and 9.08×10-6 respectively, compared with the end of refining, due to the lack of protective pouring during the casting process of the large ingot. The number density of inclusions increases nearly 4 times, and the inclusions are also transformed from liquid calcium aluminates to Al2O3, which reduces the calcium treatment effect after reoxidation. The average rate of air involved in the molten steel surface of the tundish during pouring obtained through numerical simulation is 4.2×10-5 kg/s. The temperature difference is 3.9 K between the inlet and outlet of the tundish due to deep level of round tundish. After reoxidation, the TO mass fraction in the injection zone is higher, and the mass fraction is lower in the circulation flow region on the right and near the bottom. The average and maximum TO mass fraction are 28.6×10-6 and 45.3×10-6, respectively, and the average mass fraction of CaO and Al2O3 are 20.9×10-6 and 32.3×10-6, respectively, providing theoretical guidance for optimizing the reoxidation of molten steel during the casting process of tundish.
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2023, Vol. 33 
