Kinetics of Transformation of Al{sub 2}O{sub 3} to MgO·Al{sub 2}O{sub 3} Spinel Inclusions in Mg-Containing Steel
- Tohoku University, Department of Metallurgy, Graduate School of Engineering (Japan)
- Central Japan Railway (Japan)
- Tohoku University, Institute of Multidisciplinary Research for Advanced Materials (Japan)
- Chosun Unversity, Department of Materials Science & Engineering, College of Engineering (Korea, Republic of)
- University of Science and Technology Beijing, School of Metallurgical and Ecological Engineering (China)
During ladle furnace refining, initial Al{sub 2}O{sub 3} inclusions generally transform into MgO·Al{sub 2}O{sub 3} spinel inclusions; these generated spinel inclusions consequently deteriorate the product quality. In this study, the transformation from Al{sub 2}O{sub 3} to MgO·Al{sub 2}O{sub 3} was investigated by immersing an Al{sub 2}O{sub 3} rod into molten steel, which was in equilibrium with both MgO and MgO·Al{sub 2}O{sub 3} spinel-saturated slag. A spinel layer, with a thickness of 4 μm, was generated on the Al{sub 2}O{sub 3} rod surface just 10 s after its immersion at 1873 K (1600 °C). The thickness of the formed spinel layer increased with the immersion period and temperature. Moreover, the MgO content of the generated spinel layer also increased with the immersion period. In this study, the chemical reaction rate at 1873 K (1600 °C) was assumed to be sufficiently high, and only diffusion was considered as a rate-controlling step for this transformation. By evaluating the activation energy, MgO diffusion in the generated spinel layer was found to be the rate-controlling step. In addition, this estimation was confirmed by observing the Mg and Al concentration gradients in the generated spinel layer. The results of this study suggest that the MgO diffusion in the spinel inclusions plays a substantial role with regard to their formation kinetics.
- OSTI ID:
- 22858100
- Journal Information:
- Metallurgical and Materials Transactions B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions B, Process Metallurgy and Materials Processing Science Journal Issue: 1 Vol. 49; ISSN 1073-5615; ISSN MTBSEO
- Country of Publication:
- United States
- Language:
- English
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