Evolution of inclusions in IF steel during continuous casting process

Hao Xiaoshuai; Bai Xuefeng; Sun Yanhui; Guo Zhijie; Zeng Jianhua; Zhang Min; Wu Chenhui

doi:10.7513/j.issn.1004-7638.2022.03.026

Volume 43 Issue 3

Jun. 2022

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Hao Xiaoshuai, Bai Xuefeng, Sun Yanhui, Guo Zhijie, Zeng Jianhua, Zhang Min, Wu Chenhui. Evolution of inclusions in IF steel during continuous casting process[J]. IRON STEEL VANADIUM TITANIUM, 2022, 43(3): 167-175. doi: 10.7513/j.issn.1004-7638.2022.03.026

Citation:

Hao Xiaoshuai, Bai Xuefeng, Sun Yanhui, Guo Zhijie, Zeng Jianhua, Zhang Min, Wu Chenhui. Evolution of inclusions in IF steel during continuous casting process[J]. IRON STEEL VANADIUM TITANIUM, 2022, 43(3): 167-175. doi: 10.7513/j.issn.1004-7638.2022.03.026

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Evolution of inclusions in IF steel during continuous casting process

doi: 10.7513/j.issn.1004-7638.2022.03.026

1.
Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China
2.
Pangang Group Research Institute Co., Ltd., Panzhihua 617000, Sichuan, China

Received Date: 2022-03-24
Publish Date: 2022-06-30

Abstract

Abstract

The evolution of inclusions in steel of the continuous casting process of IF steel produced by a plant was studied by systematically sampling including molten steel and casting billet. The methods of analysis mainly include analysis of total oxygen and nitrogen content, ASPEX scanning electron microscope-spectrometer and thermodynamic calculations. The results show that the content of total oxygen in steel during continuous casting process presents a total decreasing trend. But there is a secondary oxidation of molten steel by covering agent or resistant material at the opening stage of tundish. The composition of covering agent or lining should be adjusted appropriately, so as to make the content of T.O and [N] in casting slab is 12×10⁻⁶ and 21×10⁻⁶, respectively, which meet the control requirements of IF steel. The trend of the number density of inclusions in steel during the continuous casting process is consistent with the trend of total oxygen content. The increase of the number density of inclusions in slab is subject to TiN precipitation during solidification and cooling. The number density of inclusions in the molten steel in the tundish injection area is lower than that in the pouring area during the entire tundish process, whose size is larger. With the pouring, the content of MgO of inclusions in the molten steel of tundish gradually increases, and shows a negative correlation with the size, and the inclusions larger than 10 μm are concentrated in the area with high Al₂O₃ content. Thermodynamic calculation results show that the stable inclusion phase in the molten steel at 1 600 °C is only Al₂O₃, but some Al₂O₃−TiO_x inclusions are found in the experimental results, which is due to the addition of titanium alloys in the RH refining process causing the local Ti concentration to be too high, which provides conditions for the formation of TiO_x and Al₂O₃−TiO_x. There are TiS-containing inclusions in slab, including pure TiS inclusions and composite inclusions of Al₂O₃−TiS and TiS-TiN, and the size of such inclusions decreases with the increase of mass fraction of TiS.
- IF steel,
- continuous casting,
- non-metallic inclusions,
- evolution,
- thermodynamic calculation

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References(20)

References

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