Argon solubility in molten iron
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Fig. 1—The dependence of carbon dissolution rate constant on crystallite size Lc for coals.
to a significant increase in the rate of carbon dissolution. On the other hand, carbon transfer in the liquid boundary may become a relatively slower step. The rate of carbon dissolution is, therefore, controlled by carbon diffusion in the liquid boundary layer. For carbonaceous materials with relatively low Lc values, such as coals (assuming that obtaining carbon atoms from the 3-D network is one of the rate-limiting steps in the overall carbon dissolution process), with an increase of Lc, there is an improvement in the ordering of carbon atom arrangement. It will result in an increase in the rate of carbon atom dissociation from the site where it was held. The rate of carbon dissolution could be significantly enhanced accordingly by increasing the carbonconcentration gradient in the liquid boundary layer. It is worth noting that the existence of ash in carbonaceous materials does have a retarding effect on carbon dissolution from coals, and it must be taken into account in carbon dissolution studies. However, this study has demonstrated that crystallite size, Lc, would be a good additional criterion with which to assess carbon dissolution performance of coals with comparable chemical compositions.
REFERENCES 1. V. Sahajwalla, I.F. Taylor, J.K. Wright, and G.J. Hardie: Metallurgical Processes for Early Twenty First Century, TMS, Warrendale, PA, 1994, pp. 715-29. 2. J.K. Wright and I.F. Taylor: Iron Steel Inst. Jpn. Int., 1993, vol. 33 (5), pp. 529-38. 3. Y. Shigeno, M. Tokuda, and M. Ohtani: Trans. Jpn. Inst. Met., 1985, vol. 26 (1), pp. 33-43. 4. R. Diamond: Acta Cryst., 1958, vol. 11, pp. 129-38. 5. M.W. Haenel: Fuel, 1992, vol. 71 (11), pp. 1211-23. 6. D.W. Van Krevelen: Coal, Typology-Physics-Chemistry-Constitution, 3rd ed., Elsevier, Amsterdam, Netherlands, 1993, pp. 225-46. 7. H.E. Bladen, J. Gibson, and H.L. Riley: Proc. Conf. Ultrafine Structure of Coal and Coke, London, 1944, p. 176. 8. B.D. Cullity: Elements of x-ray Diffraction, Addison-Wesley Publishing Co., Reading 2nd ed., 1978, pp. 107-45. 9. C. Wu and V. Sahajwalla: in Metall. Mater. Trans. B, in press. 10. T. Green and J. Kovac: Coal Structure, R.A. Meyers, ed., Academic Press, New York, NY, 1982, pp. 199-282. 11. P.B. Hirsch, A. Howie, R.B. Nicholson, D.W. Pashley, and M.J. Whelan: Electron Microscopy of Thin Crystals, Butterworth and Co., London, 1965, pp. 1-338. 216—VOLUME 31B, FEBRUARY 2000
Fine argon bubbles were sometimes observed in the surface layer of continuous cast low carbon steel slabs.[1] In the subsequent rolling process, these argon bubbles can lead to formation of blowhole defects. As argon is commonly used in the submerged entry nozzle (SEN) to reduce nozzle clogging, possible argon bubble entrainment in liquid steel in the casting mold becomes an obvious culprit. However, it has been found that argon bubbles can also be present when argon flushing of the SEN is not applied.[1] It thus appears that the source of the argon bubble in the
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