Formation kinetics of iron oxide in mould flux during continuous casting

Min Wang, Yoshinao Kobayashi, Rie Endo, Masahiro Susa

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The present work aims to understand the mechanism and rate of iron oxide formation in molten mould flux initially having no iron oxide to discuss how to keep the mild cooling performance of the flux. The concentration change of iron oxides in mould fluxes was measured at 1 891 K as a function of time in variations of three physico-chemical conditions: (i) oxygen partial pressures in atmospheres (air and argon), (ii) SiO2 activities in mould fluxes and (iii) oxygen concentrations in molten irons, the last being provided by Al-killed and non-killed operations on electrolytic iron samples. The following findings have been obtained: (i) iron oxide concentrations increase with holding time and reach ca 3.5 mass% within 1.8 ks, independently of atmospheres, (ii) higher SiO2 activity leads to higher viscosity of mould flux and lower iron oxide concentrations and (iii) iron oxide concentrations decrease to ca 0.5 mass% due to lower oxygen concentrations in molten Al-killed iron. Thus, the following mechanism has been proposed: oxygen dissolved in molten iron is primarily oxygen source and reacts with iron to form iron oxides at the metal/flux interface, which oxides diffuse into molten flux phase. A kinetic discussion has given the total reaction rate constant as k = 7.5 . 10-6 cm·s-1 and suggested that the rate be dominated by iron oxide transfer through the boundary layer. To suppress iron oxide formation, additions of reducing agents would be more efficient than controls of oxygen partial pressures.

Original languageEnglish
Pages (from-to)56-61
Number of pages6
JournalISIJ International
Volume53
Issue number1
DOIs
Publication statusPublished - 2013
Externally publishedYes

Keywords

  • Continuous casting
  • Formation kinetics
  • Iron oxide
  • Mild cooling
  • Mould flux

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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