Abstract
Ladle slag affects steel cleanliness at the end of the Ruhrstahl-Hereaeus (RH) and holding process. The relationship between composition of ladle slag, total oxygen (TO) and inclusions was investigated using X-ray fluorescence (XRF), infrared absorption, and SEM + EDS methods. The results indicate that TO in steel at the end of RH increases linearly with increasing FeO content in slag. TO is lower when wCaO/ wAl2O3 (C/A) = 1.5–2.0 than that of C/A=1.0–1.4 under an approximate content of FeO. During the holding process, irregular Al2O3 inclusions are newly generated due to slag reoxidation. Additionally, Al2O3-TixO inclusions are newly generated in the steel when the content of FeO is higher. By combining experimental and thermodynamic calculation results, it is determined that the slag has a good melting property within the zone of C/A=1.2–1.8 and adsorption capacity of Al2O3 when the content of SiO2 in slag is controlled at 4% – 6%. The increase in the C/A ratio and the decrease of FeO content in slag can slow down the reoxidation rate.
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Abbreviations
- Rd:
-
Absorption capacity of slag
- K:
-
Mass transfer coefficient related to melting point, μm • s−1
- Cs:
-
Saturation fraction of Al3O3 in slag, wt. %
- Cb:
-
Real mass fraction of Al2O3, in slag, wt. %
- JS:
-
Diffusion flux of FeO in slag, mol • cm−2 • s−1
- Jm:
-
Diffusion flux of FeO in steel, mol • cm−2 • s−1
- kS:
-
Mass transfer coefficient of FeO in slag, cm−2 • s−1
- kM:
-
Mass transfer coefficient of FeO in steel, cm • s−1
- c(FeO):
-
Concentration of FeO in slag, mol • cm−3
- c(FeO)i:
-
Concentration of FeO at steel/slag interface, mol • cm−3
- c[O]:
-
Concentration of [O] in steel, mol • cm−3
- c[O]i:
-
Concentration of [O] at steel/slag interface, mol • cm−3.
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Wang, R., Bao, Yp., Li, Yh. et al. Effect of slag composition on steel cleanliness in interstitial-free steel. J. Iron Steel Res. Int. 24, 579–585 (2017). https://doi.org/10.1016/S1006-706X(17)30088-2
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DOI: https://doi.org/10.1016/S1006-706X(17)30088-2