TY - JOUR
T1 - Morphology and composition of inclusions in Si-Mn deoxidized steel at the solid-liquid equilibrium temperature
AU - Gamutan, Jonah
AU - Miki, Takahiro
AU - Nagasaka, Tetsuya
N1 - Funding Information:
Technology (MEXT) for the corresponding author’s financial support during her graduate studies. Recognition is also extended to Professor Takehito Hiraki, Professor Yasushi Sasaki and Professor Elizabeth Webeck for their valuable help and encouragement.
Publisher Copyright:
© 2020 Iron and Steel Institute of Japan. All rights reserved.
PY - 2020
Y1 - 2020
N2 - Morphology and composition of inclusions change with temperature. However, besides the temperature conditions during steelmaking or continuous casting, other factors contributing to changes in the morphology and composition of inclusions during solidification are still unknown. In this study, the formation of complex inclusions in Si-Mn deoxidized steel after isothermal holding at the solid-liquid equilibrium temperature (TS) was investigated. The typical inclusions found in the alloy were MnO-SiO2 based, spherically shaped and homogeneously distributed. With isothermal holding at the solid-liquid equilibrium temperature, formation of a secondary SiO2-rich inclusion phase occurred. The changes in the composition of the inclusions depended on the manganese and silicon contents in the metal. The general mechanism of inclusion formation observed in this study can be divided into three steps: 1) the formation of primary MnO-SiO2 inclusions above the liquidus temperature when the steel is in a completely molten state as a result of the deoxidation process; 2) the nucleation of secondary inclusions as the molten steel becomes supersaturated with the solute elements while holding at the solid-liquid equilibrium temperature; and 3) the growth and coalescence of inclusions due to natural convection in the molten alloy. From this, the inclusions formed in Si-Mn deoxidized alloys held isothermally at the solid-liquid equilibrium temperature were of three types: primary MnO-SiO2 inclusions, secondary SiO2 inclusions and complex inclusions with both primary MnO-SiO2 inclusions and precipitated secondary SiO2 inclusions.
AB - Morphology and composition of inclusions change with temperature. However, besides the temperature conditions during steelmaking or continuous casting, other factors contributing to changes in the morphology and composition of inclusions during solidification are still unknown. In this study, the formation of complex inclusions in Si-Mn deoxidized steel after isothermal holding at the solid-liquid equilibrium temperature (TS) was investigated. The typical inclusions found in the alloy were MnO-SiO2 based, spherically shaped and homogeneously distributed. With isothermal holding at the solid-liquid equilibrium temperature, formation of a secondary SiO2-rich inclusion phase occurred. The changes in the composition of the inclusions depended on the manganese and silicon contents in the metal. The general mechanism of inclusion formation observed in this study can be divided into three steps: 1) the formation of primary MnO-SiO2 inclusions above the liquidus temperature when the steel is in a completely molten state as a result of the deoxidation process; 2) the nucleation of secondary inclusions as the molten steel becomes supersaturated with the solute elements while holding at the solid-liquid equilibrium temperature; and 3) the growth and coalescence of inclusions due to natural convection in the molten alloy. From this, the inclusions formed in Si-Mn deoxidized alloys held isothermally at the solid-liquid equilibrium temperature were of three types: primary MnO-SiO2 inclusions, secondary SiO2 inclusions and complex inclusions with both primary MnO-SiO2 inclusions and precipitated secondary SiO2 inclusions.
KW - Complex inclusion formation
KW - Microsegregation
KW - Si-Mn deoxidation
KW - Solid-liquid equilibrium temperature
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U2 - 10.2355/isijinternational.ISIJINT-2019-313
DO - 10.2355/isijinternational.ISIJINT-2019-313
M3 - Article
AN - SCOPUS:85078541329
VL - 60
SP - 84
EP - 91
JO - Transactions of the Iron and Steel Institute of Japan
JF - Transactions of the Iron and Steel Institute of Japan
SN - 0915-1559
IS - 1
ER -