Advertisement

Metallurgical Transactions A

, Volume 13, Issue 11, pp 1939–1950 | Cite as

The role of nitrogen in the embrittlement of steel

  • C. L. Briant
  • S. K. Banerji
  • A. M. Ritter
Mechanical Behavior

Abstract

Nitrogen is one of the most common impurity elements to be found in steels. Previous work has shown that it is a potential grain boundary embrittler. In this paper we examine its role in both tempered martensite embrittlement and temper embrittlement. The basic composition of the steel used for this study was, in wt pct, 3.5 Ni, 1.7 Cr, 0.3 C, and 0.01 N. It was found that nitrogen could be very detrimental to mechanical properties but not as a grain boundary embrittler in the typical sense that P, Sn, and Sb are. Rather, nitrogen is almost always precipitated as nitrides and these second phase particles can induce low energy ductile fracture. The distribution of nitrides in the solid and the type of nitride present is dependent on the heat treatment. If a low austenitizing temperature is used, the nitrides in the steel dissolve and considerable nitrogen segregates to the grain boundaries. During an oil quench it reprecipitates at the boundaries, primarily as Cr2N. These nitrides cause low energy, ductile intergranular fracture. If a high austenitizing temperature is used, much less nitrogen segregrates so fewer nitrides precipitate during the quench. However, upon tempering the nitrogen does reprecipitate. At low tempering temperatures, small nitrides form both within the grains and along the grain boundaries. When these nitrides become sufficiently large, voids form around them as well as around the carbides during fracture. These small voids help link the large voids that form around oxide and sulfide particles and lower the energy for ductile fracture. After high temperature tempering treatments large nitrides and carbides form at the grain boundaries. These produce low energy, intergranular ductile fracture. These large grain boundary precipitates can also aid in brittle intergranular fracture by providing many more sites for nucleation of intergranular cracks when the boundary is weakened by another impurity element.

Keywords

Metallurgical Transaction Fracture Energy Ductile Fracture Intergranular Fracture Peak Height Ratio 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    J. M. Capus:Metallurgia, 1960, vol. 62, p. 133.Google Scholar
  2. 2.
    B. E. Hopkins and H. R. Tipler:J. Iron Steel Institute, 1954, vol. 177, p. 110.Google Scholar
  3. 3.
    S. K. Banerji, H. C. Feng, and C. J. McMahon,Jr.: Metall. Trans. A, 1978, vol. 9A, p. 237.Google Scholar
  4. 4.
    B.C. Edwards, M. Nasim, and E. A. Wilson:Scripta Met., 1978, vol. 12, p. 377.CrossRefGoogle Scholar
  5. 5.
    C. L. Briant, C. J. McMahon, Jr., and H. C. Feng:Metall. Trans. A, 1978, vol. 9A, p. 625.Google Scholar
  6. 6.
    T. Inoue:Grain Boundaries in Engineering Materials, J. L. Walter,et al, eds., Claitors Publishing Division, Baton Rouge, LA, 1975, p. 553.Google Scholar
  7. 7.
    J. A. Wright and A. G. Quarrell:J. Iron Steel Institute, 1954, vol. 177, p. 110.Google Scholar
  8. 8.
    G. J. Spaeder, R.M. Brown, and W. J. Murphy:Trans. ASM, 1967, vol. 60, p.418.Google Scholar
  9. 9.
    John F. Grubb and Roger W. Wright:Metall. Trans. A, 1979, vol. 10A, p. 1247.Google Scholar
  10. 10.
    A. Plumtree and R. Gullberg:Metall. Trans. A, 1976, vol. 7A, p. 1451.Google Scholar
  11. 11.
    A. Plumtree and R. Gullberg:J. Testing Eval., 1974, vol. 2, p. 331.CrossRefGoogle Scholar
  12. 12.
    B. Pollard:Met. Technol., 1974, vol. 1, p. 31.Google Scholar
  13. 13.
    S. Takayama, T. Ogura, S-C Fu, and C.J. McMahon, Jr.:Metall. Trans. A, 1980, vol. 11A, p. 1513.Google Scholar
  14. 14.
    R. A. Mulford, C. J. McMahon, Jr., D. P. Pope, and H. C. Feng:Metall. Trans. A, 1976, vol. 7A, p. 1183 and p. 1269.Google Scholar
  15. 15.
    A. H. Ucisik, C. J. McMahon, Jr., and H. C. Feng:Metall. Trans. A, 1978, vol. 9A, p. 321.Google Scholar
  16. 16.
    C.L. Briant and S.K. Banerji:Metall. Trans. A, 1979, vol. l0A, p. 1729.Google Scholar
  17. 17.
    C. L. Briant and S. K. Banerji: International Metals Review, 1978, vol. 23, p. 164.Google Scholar
  18. 18.
    C. L. Briant and S. K. Banerji:Metall. Trans. A, 1982, vol. 13A, p. 827.Google Scholar
  19. 19.
    E. B. Kula and A. A. Anctil:J. Materials, 1969, vol. 4, p. 817.CrossRefGoogle Scholar
  20. 20.
    G. Thomas:Metall. Trans. A, 1978, vol. 9A, p. 439.Google Scholar
  21. 21.
    R.M. Horn and R.O. Ritchie:Metall. Trans. A, 1978, vol. 9A, p. 1039.Google Scholar
  22. 22.
    J.E. King, R. F. Smith, and J.F. Knott:Fracture 1977-1CF4, D. M. R. Taplin, ed., Waterloo, University of Waterloo Press, 1977, vol. 2, p. 279.Google Scholar
  23. 23.
    C. Pichard, J. Rieu, and C. Goux:Mem. Sci. Revue Metall., 1973, vol. 70, p. 13.Google Scholar
  24. 24.
    T. B. Cox and J. R. Low, Jr.:Metall. Trans., 1974, vol. 5, p. 1457.Google Scholar
  25. 25.
    B.J. Schulz and C.J. McMahon, Jr.:Metall. Trans., 1973, vol. 4, p. 2485.Google Scholar

Copyright information

© American Society for metals and the metallurgical society of AIME 1982

Authors and Affiliations

  • C. L. Briant
    • 1
  • S. K. Banerji
    • 2
  • A. M. Ritter
    • 1
  1. 1.Corporate Research and DevelopmentGeneral Electric CompanySchenectady
  2. 2.Foote Mineral CompanyExton

Personalised recommendations