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Journal of Materials Science

, Volume 20, Issue 2, pp 718–729 | Cite as

Excess nitrogen and discontinuous precipitation in nitrided iron-chromium alloys

  • P. M. Hekker
  • H. C. F. Rozendaal
  • E. J. Mittemeijer
Article

Abstract

FeCr (1.88 and 3.61 wt % Cr) specimens were gas nitrided (10 vol % NH3/90 vol % H2 gas mixture at 833 K). The structure after nitriding was studied employing metallographic methods (optical microscopy, hardness measurements), scanning electron microscopy and X-ray diffractometry (residual macrostress determination and phase identification). Further the weight and thickness increases of the specimens during nitriding were determined. Excess nitrogen uptake, discontinuous precipitation and void formation were observed. The amount of excess nitrogen observed in an initial stage of precipitation corresponds well with the predicted amount applying thermodynamics of stressed solids. The occurrence of a discontinuous precipitation reaction at later stages of precipitation was accompanied by the loss of excess nitrogen from the supersaturated ferritic matrix. In this way void formation and changes in the residual macrostress distribution within the specimen during nitriding can be explained. As a result a model is presented for the description of the nitriding behaviour of Fe-Cr alloys.

Keywords

Nitrided Nitrogen Uptake Ferritic Matrix Void Formation Discontinuous Precipitation 
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.

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References

  1. 1.
    E. T. Turkdogan andS. Ignatowicz,J. Iron Steel Inst. 188 (1958) 242.Google Scholar
  2. 2.
    J. R. Atanassova,Harterei-Tech. Mitt. 31 (1976) 325.Google Scholar
  3. 3.
    E. J. Mittemeijer, H. C. F. Rozendaal, P. F. Colijn, P. J. Van Der Schaaf andR. Th. Furnée, Proceedings of the Conference on Heat Treatment 1981, Birmingham, UK, 1981 (The Metals Society London, 1983) p. 107.Google Scholar
  4. 4.
    E. J. Mittemeijer, A. B. P. Vogels andP. J. Van Der Schaaf,J. Mater. Sci. 15 (1980) 3129.Google Scholar
  5. 5.
    B. Mortimer, P. Grieveson andK. H. Jack,Scand. J. Met. 1 (1972) 203.Google Scholar
  6. 6.
    H. P. Klug andL. E. Alexander, “X-Ray Diffraction Procedures”, 2nd edn (John Wiley and Sons, New York, 1974) p. 755.Google Scholar
  7. 7.
    R. Delhez andE. J. Mittemeijer,J. Appl. Crystallogr. 8 (1975) 609.Google Scholar
  8. 8.
    M. G. Moore andW. P. Evans,SAE Trans. 66 (1958) 340.Google Scholar
  9. 9.
    P. F. Colijn, E. J. Mittemeijer andH. C. F. Rozendaal,Z. Metallkd. 74 (1983) 620.Google Scholar
  10. 10.
    E. J. Mittemeijer,Härterei-Tech. Mitt. 36 (1981) 57.Google Scholar
  11. 11.
    J. L. Meijering, “Advances in Material Research”, Vol. 5 (Wiley Interscience, New York, 1971) p. 1.Google Scholar
  12. 12.
    J. D. Fast andM. B. Verrijp,J. Iron Steel Inst. 176 (1954) 24.Google Scholar
  13. 13.
    B. J. Lightfoot andD. H. Jack, Proceedings of the Conference on Heat Treatment, 1973 (The Metals Society, London, 1975) p. 59.Google Scholar
  14. 14.
    D. B. Williams andE. P. Butler,Int. Met. Rev. 26 (1981) 153.Google Scholar
  15. 15.
    D. H. Jack,Acta Metall. 24 (1976) 137.Google Scholar
  16. 16.
    H. H. Podgurski andF. N. Davis,ibid. 29 (1981) 1.Google Scholar
  17. 17.
    D. S. Rickerby, A. Hendry andK. H. Jack, Proceedings of the Conference on Heat Treatment 1981 Birmingham, UK, 1981 (The Metals Society, London 1983) p. 130.Google Scholar
  18. 18.
    V. A. Phillips andA. U. Seybolt,Trans. AIME 242 (1968) 2415.Google Scholar
  19. 19.
    K. H. Jack, Proceedings of the Conference on Heat Treatment, 1973 (The Metals Society, London, 1975) p. 39.Google Scholar
  20. 20.
    E. J. Mittemeijer, P. Van Mourik andTh. H. De Keijser,Phil. Mag. A 43 (1981) 1157.Google Scholar
  21. 21.
    E. J. Mittemeijer, Proceedings of the Conference on Heat Treatment 1981 Birmingham, UK, 1981 (The Metals Society, London, 1983). p. 164.Google Scholar
  22. 22.
    E. J. Mittemeijer, M. Van Rooyen, I. Wierszyllowski, H. C. F. Rozendaal andP. F. Colijn,Z. Metallkd. 74 (1983) 473.Google Scholar
  23. 23.
    J. C. M. Li, R. A. Oriani andL. S. Darken,Z. Phys. Chem. 49 (1966) 271.Google Scholar
  24. 24.
    O. Richmond, as cited in [16].Google Scholar
  25. 25.
    W. B. Pearson, “A Handbook of Lattice Spacings and Structures of Metals and Alloys”, Vol. 1 (Pergamon Press, London, 1958) p. 625.Google Scholar
  26. 26.
    E. J. Mittemeijer, Proceedings of the TMS/AIME Symposium on Case-Hardened Steels: Microstructural and Residual Stress Effects, Atlanta, Georgia, USA, March 1983 (TMS/AIME, 1984).Google Scholar
  27. 27.
    E. J. Mittemeijer,J. Heat Treating 3 (1983) 114.Google Scholar

Copyright information

© Chapman and Hall Ltd 1985

Authors and Affiliations

  • P. M. Hekker
    • 1
  • H. C. F. Rozendaal
    • 1
  • E. J. Mittemeijer
    • 1
  1. 1.Laboratory of MetallurgyDelft University of TechnologyAL DelftThe Netherlands

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