The electroslag remelting process (ESR) represents a viable approach for the production of large-scale rack steels. However, the continued advancement of this technique is hindered by the challenge of managing complex elemental burnout issues. In this study, the high-temperature short-term oxidation mechanism of rack steel in air at 900 °C, 1000 °C, 1100 °C, 1200 °C, and 1300 °C for 30 minutes were investigated using isothermal oxidation tests. The phase composition of the oxide scale was determined by X-ray diffraction (XRD) and Raman spectroscopy, and the cross-sectional microstructure and cross-sectional element distribution of the rack steel were characterized by electron probe microanalysis (EPMA). The results demonstrate that the kinetic curves of isothermal oxidation obtained at different temperatures follow the parabolic law, with an activation energy of oxidation Q of 197.17 KJ/mol. It can be concluded that the oxidation rate is controlled by the outward diffusion of alloying elements and the inward diffusion of oxygen. The oxide scale was primarily constituted of iron oxides (Fe2O3, Fe3O4, FeO), SiO2, TiO2, Fe2SiO4, and FeCr2O4. At temperatures of 900 °C, 1000 °C, and 1100 °C, no discernible internal oxidation was observed. At temperatures of 1200 °C and 1300 °C, the continuous external oxide layer exhibited severe internal oxidation beneath it, with the oxide spots and long stripes of oxides identified as SiO2. This phenomenon is primarily attributed to the penetration of molten Fe2SiO4 into the matrix and the exfoliation of the outer TiO2 layer, which provides a channel for oxygen diffusion. Furthermore, as the oxidation process continues, further decomposition of FeO, O2 dissolved in the matrix, and diffusion to the inner side of the matrix prevail, completing the transition from external to internal oxidation. The oxidation mechanism model of rack and pinion steel has also been proposed as a means of providing a theoretical basis for the reduction of electrode oxidation and precise control of the content of alloying elements in ingot during the electroslag remelting process. This should result in a reduction in the dosage of deoxidizing agent and a reduction in the smelting cost of the electroslag remelting process. It represents an important reference value for the development of corresponding protective measures against elemental burnout in the electroslag remelting process.

High-Temperature Oxidation Mechanism of Rack Steel During Electroslag Remelting Process

期刊论文
发表日期：

2025年2月3日

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Xiangxiang Xie,
Wanming Li,
Ximin Zang,
Baoxi Liu,
Zefeng Liu

摘要

The electroslag remelting process (ESR) represents a viable approach for the production of large-scale rack steels. However, the continued advancement of this technique is hindered by the challenge of managing complex elemental burnout issues. In this study, the high-temperature short-term oxidation mechanism of rack steel in air at 900 °C, 1000 °C, 1100 °C, 1200 °C, and 1300 °C for 30 minutes were investigated using isothermal oxidation tests. The phase composition of the oxide scale was determined by X-ray diffraction (XRD) and Raman spectroscopy, and the cross-sectional microstructure and cross-sectional element distribution of the rack steel were characterized by electron probe microanalysis (EPMA). The results demonstrate that the kinetic curves of isothermal oxidation obtained at different temperatures follow the parabolic law, with an activation energy of oxidation Q of 197.17 KJ/mol. It can be concluded that the oxidation rate is controlled by the outward diffusion of alloying elements and the inward diffusion of oxygen. The oxide scale was primarily constituted of iron oxides (Fe₂O₃, Fe₃O₄, FeO), SiO₂, TiO₂, Fe₂SiO₄, and FeCr₂O₄. At temperatures of 900 °C, 1000 °C, and 1100 °C, no discernible internal oxidation was observed. At temperatures of 1200 °C and 1300 °C, the continuous external oxide layer exhibited severe internal oxidation beneath it, with the oxide spots and long stripes of oxides identified as SiO₂. This phenomenon is primarily attributed to the penetration of molten Fe₂SiO₄ into the matrix and the exfoliation of the outer TiO₂ layer, which provides a channel for oxygen diffusion. Furthermore, as the oxidation process continues, further decomposition of FeO, O₂ dissolved in the matrix, and diffusion to the inner side of the matrix prevail, completing the transition from external to internal oxidation. The oxidation mechanism model of rack and pinion steel has also been proposed as a means of providing a theoretical basis for the reduction of electrode oxidation and precise control of the content of alloying elements in ingot during the electroslag remelting process. This should result in a reduction in the dosage of deoxidizing agent and a reduction in the smelting cost of the electroslag remelting process. It represents an important reference value for the development of corresponding protective measures against elemental burnout in the electroslag remelting process.