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Metallurgical and Materials Transactions A

, Volume 38, Issue 9, pp 1991–2000 | Cite as

X-ray Diffraction Study on Cooling-Rate-Induced γ fccε hcp Martensitic Transformation in Cast-Homogenized Fe-26Mn-0.14C Austenitic Steel

  • P. SahuEmail author
  • A.S. Hamada
  • R.N. Ghosh
  • L.P. Karjalainen
Article

Abstract

The thermal stability of a cast homogenized austenitic steel with basic composition Fe-26Mn-0.14C has been studied using the Rietveld entire X-ray diffraction (XRD) pattern fitting technique. The decomposition of austenite was observed to be very sensitive to the cooling rate. A very high proportion (49 to 70 pct) of ε-martensites was found in the differently cooled specimens as well in the as-cast specimen. The density of various planar (stacking and twin) faults was also estimated in both ε-martensites and retained austenite. The significant variation in the extent of γ fccε hcp martensitic transformation was interpreted in terms of athermal and isothermal martensites formed during cooling and grain size of austenite. The austenite grains were found to be comprised of a high to moderate density of stacking faults (∼10−3 to 10−2) and negligible twin fault probability (∼10−5). On the other hand, in the ε-martensites, the dominant planar fault was twins (∼10−3). Approximate values of the dislocation density within the retained austenite were also evaluated using the crystallite size and root-mean-square (rms) strain values obtained from the “size-strain-shape” analyses.

Keywords

Austenite Martensite Crystallite Size Dislocation Density Stack Fault Energy 
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

Acknowledgments

Two of the authors (PS and RNG) are grateful to Professor S.P. Mehrotra, Director, National Metallurgical Laboratory, Jamshedpur, for his kind permission to publish the results.

References

  1. 1.
    Y. Tomota, M. Strum, J.W. Morris Jr.: Metall. Trans. A, 1986, vol. 17A, pp. 537–47Google Scholar
  2. 2.
    Y.G. Kim, J.M. Han, J.S. Lee: Mater. Sci. Eng. A, 1989, vol. 114, pp. 51–59CrossRefGoogle Scholar
  3. 3.
    A. Sato, K. Soma, T. Mori: Acta Metall., 1982, vol. 30, pp. 1901–07CrossRefGoogle Scholar
  4. 4.
    H. Schumann: Arch. Eisenhüttenwes, 1969, vol. 40, pp. 1027–37Google Scholar
  5. 5.
    A. Seeger: Metallkd., 1956, vol. 47, pp. 653–60Google Scholar
  6. 6.
    Y. Hoshino, S. Nakamura, N. Ishikawaand, A. Sato: Mater. Sci. Forum, 1990, vols. 56–58, pp. 643–48CrossRefGoogle Scholar
  7. 7.
    G.B. Olson, M. Cohen: Metall. Trans. A, 1976, vol. 7A, pp. 1897–904Google Scholar
  8. 8.
    T.Y. Hsu, Xu Zuyao: Acta Metall. Sinica, 1980, vol. 16, pp. 430–34Google Scholar
  9. 9.
    K. Sato, M. Ichinose, Y. Hirotsu, Y. Inoue: ISIJ Int., 1989, vol. 29, pp. 868–77Google Scholar
  10. 10.
    K. Ishida, T. Nishizawa: Trans. Jpn. Inst. Met., 1974, vol. 15, pp. 225–31Google Scholar
  11. 11.
    R.E. Schramm, R.P. Reed: Metall. Trans. A, 1975, vol. 6A, pp. 1345–51Google Scholar
  12. 12.
    H.M. Rietveld: J. Appl. Cryst., 1969, vol. 2, pp. 65–71CrossRefGoogle Scholar
  13. 13.
    L. Lutterotti: MAUD, version 2.038, http://www.ing.unitn.it/∼luttero/maud, 2006
  14. 14.
    P. Sahu: J. Appl. Cryst., 2005, vol. 38, pp. 112–20CrossRefGoogle Scholar
  15. 15.
    T. Sawaguchi, P. Sahu, T. Kikuchi, K. Ogawa, S. Kajiwara, A. Kushibe, M. Higashino, T. Ogawa: Scripta Mater., 2006, vol. 54, pp. 1885–90CrossRefGoogle Scholar
  16. 16.
    P. Sahu: Intermetallics, 2006, vol. 14, pp. 180–88CrossRefGoogle Scholar
  17. 17.
    J.G.M. Van Berkum, G.J.M. Sprong, T.H. de Keijser, R. Delhez, E.J. Sonneveld: Powder Diffrac., 1995, vol. 10, pp. 129–39Google Scholar
  18. 18.
    R.A. Young: in The Rietveld Method, R.A. Young, ed., Oxford University Press, Oxford, United Kingdom, 1993, ch. 1Google Scholar
  19. 19.
    L. Lutterotti, P. Scardi, P. Maitrelli: J. Appl. Cryst., 1990, vol. 23, pp. 246–52CrossRefGoogle Scholar
  20. 20.
    N.C. Popa: J. Appl. Cryst., 1998, vol. 31, pp. 176–80CrossRefGoogle Scholar
  21. 21.
    R.J. Hill, C.J. Howard: J. Appl. Cryst., 1987, vol. 20, pp. 467–74CrossRefGoogle Scholar
  22. 22.
    D.L. Bish, S.A. Howard: J. Appl. Cryst., 1988, vol. 21, pp. 86–91CrossRefGoogle Scholar
  23. 23.
    B.E. Warren: X-ray Diffraction, Addison-Wesley, Reading, MA, 1969, ch.13Google Scholar
  24. 24.
    G.K. Williamson, R.E. Smallman: Phil. Mag., 1956, vol. 1, pp. 34–46CrossRefGoogle Scholar
  25. 25.
    L.J. Mangonon, G. Thomas: Metall. Trans., 1970, vol. 1, pp. 1577–86CrossRefGoogle Scholar
  26. 26.
    G. Krauss, A.R. Marder: Metall. Trans., 1971, vol. 2, pp. 2343–57CrossRefGoogle Scholar
  27. 27.
    Metals Handbook, 10th ed., ASM, Materials Park, OH, 1990, vol. 1, p. 822Google Scholar
  28. 28.
    K. Ishida: Scripta Metall., 1977, vol. 11, pp. 237–42CrossRefGoogle Scholar
  29. 29.
    O. Grässel, G. Frommeyer, C. Derder, H. Hofmann: J. Phys. France, 1997, vol. 7 (C5), pp. 383–88Google Scholar
  30. 30.
    Y.K. Lee, C.S. Choi: Metall. Mater. Trans. A, 2000, vol. 31A, pp. 355–60CrossRefGoogle Scholar
  31. 31.
    A. Borgenstam, M. Hillert, J. Agren: Acta Mater., 1995, vol. 43, pp. 945–54CrossRefGoogle Scholar
  32. 32.
    A. Borgenstam, M. Hillert: Acta Mater., 1997, vol. 45, pp. 651–62CrossRefGoogle Scholar
  33. 33.
    P. Sahu, A.S. Hamada, S. Ghosh Chowdhury, L.P. Karjalainen: J. Appl. Cryst., 2007, vol. 40, pp. 354–61CrossRefGoogle Scholar
  34. 34.
    S. Ghosh Chowhury, R.K. Ray, A.K. Jena: Mater. Sci. Eng. A, 2000, vol. 277, pp. 1–10CrossRefGoogle Scholar
  35. 35.
    C. Garcia-Mateo, F.G. Caballero, H.K.D.H Bhadeshia: Mater. Sci. Forum, 2005, vols. 500–501, pp. 495–502Google Scholar

Copyright information

© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2007

Authors and Affiliations

  • P. Sahu
    • 1
    Email author
  • A.S. Hamada
    • 2
  • R.N. Ghosh
    • 1
  • L.P. Karjalainen
    • 2
  1. 1.Materials Science and Technology DivisionNational Metallurgical LaboratoryJamshedpurIndia
  2. 2.Materials Engineering Laboratory, Department of Mechanical EngineeringUniversity of OuluOuluFinland

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