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Metallurgical and Materials Transactions B

, Volume 44, Issue 2, pp 309–316 | Cite as

A Reaction Between High Mn-High Al Steel and CaO-SiO2-Type Molten Mold Flux: Part II. Reaction Mechanism, Interface Morphology, and Al2O3 Accumulation in Molten Mold Flux

  • Youn-Bae KangEmail author
  • Min-Su Kim
  • Su-Wan Lee
  • Jung-Wook Cho
  • Min-Seok Park
  • Hae-Geon Lee
Article

Abstract

Following a series of laboratory-scale experiments, the mechanism of a chemical reaction \(4[\rm{Al}] + 3(\rm{SiO}_2) = 3[\rm{Si}] + 2(\rm{Al}_2\rm{O}_3)\) between high-alloyed TWIP (TWin-Induced Plasticity) steel containing Mn and Al and molten mold flux composed mainly of CaO-SiO2 during the continuous casting process is discussed in the present article in the context of kinetic analysis, morphological evolution at the reaction interface. By the kinetic analysis using a two-film theory, a rate-controlling step of the chemical reaction at the interface between the molten steel and the molten flux is found to be mass transport of Al in a boundary layer of the molten steel, as long as the molten steel and the molten flux phases are concerned. Mass transfer coefficient of the Al in the boundary layer (\(k_{\rm{Al}}\)) is estimated to be 0.9 to 1.2 × 10−4 m/s at 1773 K (\(1500\,^{\circ}\)C). By utilizing experimental data at various temperatures, the following equation is obtained for the \(k_{\rm{Al}}; \ln k_{\rm{Al}} = -14,290/T - 1.1107.\) Activation energy for the mass transfer of Al in the boundary layer is 119 kJ/mol, which is close to a value of activation energy for mass transfer in metal phase. The composition evolution of Al in the molten steel was well explained by the mechanism of Al mass transfer. On the other hand, when the concentration of Al in the steel was high, a significant deviation of the composition evolution of Al in the molten steel was observed. By observing reaction interface between the molten steel and the molten flux, it is thought that the chemical reaction controlled by the mass transfer of Al seemed to be disturbed by formation of a solid product layer of MgAl2O4. A model based on a dynamic mass balance and the reaction mechanism of mass transfer of Al in the boundary layer for the low Al steel was developed to predict (pct Al2O3) accumulation rate in the molten mold flux.

Keywords

Al2O3 Reaction Interface Mass Transfer Coefficient MgAl2O4 Liquid Steel 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgment

This work was financially supported by POSCO Ltd. through the Steel Innovation Program (Project No. 20118060) to the Graduate Institute of Ferrous Technology, Pohang University of Science and Technology.

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Copyright information

© The Minerals, Metals & Materials Society and ASM International 2012

Authors and Affiliations

  • Youn-Bae Kang
    • 1
    Email author
  • Min-Su Kim
    • 1
  • Su-Wan Lee
    • 1
    • 3
  • Jung-Wook Cho
    • 1
    • 2
  • Min-Seok Park
    • 2
  • Hae-Geon Lee
    • 1
  1. 1.Graduate Institute of Ferrous TechnologyPohang University of Science and TechnologyPohangRepublic of Korea
  2. 2.Technical Research LaboratoriesPOSCO LtdGwangyangRepublic of Korea
  3. 3.Steelmaking Department, Pohang WorksPOSCO LtdPohangRepublic of Korea

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