Metallurgical and Materials Transactions A

, Volume 45, Issue 11, pp 4972–4982 | Cite as

Microstructural Features Controlling Mechanical Properties in Nb-Mo Microalloyed Steels. Part II: Impact Toughness

  • Nerea Isasti
  • Denis Jorge-Badiola
  • Mitra L. Taheri
  • Pello Uranga


The present paper is the final part of a two-part paper where the influence of coiling temperature on the final microstructure and mechanical properties of Nb-Mo microalloyed steels is described. More specifically, this second paper deals with the different mechanisms affecting impact toughness. A detailed microstructural characterization and the relations linking the microstructural parameters and the tensile properties have already been discussed in Part I. Using these results as a starting point, the present work takes a step forward and develops a methodology for consistently incorporating the effect of the microstructural heterogeneity into the existing relations that link the Charpy impact toughness to the microstructure. In conventional heat treatments or rolling schedules, the microstructure can be properly described by its mean attributes, and the ductile–brittle transition temperatures measured by Charpy tests can be properly predicted. However, when different microalloying elements are added and multiphase microstructures are formed, the influences of microstructural heterogeneity and secondary hard phases have to be included in a modified equation in order to accurately predict the DB transition temperature in Nb and Nb-Mo microalloyed steels.


Pearlite Impact Toughness Unit Size Polygonal Ferrite Microstructural Heterogeneity 
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.



The financial support of the Spanish Ministry of Economy and Competitiveness (MAT2009-09250 and MAT2012-31056) and the Basque Government (PI2011-17) is gratefully acknowledged.


  1. 1.
    L. Bracke, N. De Wispelaere, H. Ahmed, and O.E. Gungor: Proceedings of the International Symposium on Recent Developments in Plate Steels, 2011, pp. 131–38.Google Scholar
  2. 2.
    D.S. Liu, B.G. Cheng, and M. Luo: ISIJ Int., 2011, vol. 51, pp. 603–11.CrossRefGoogle Scholar
  3. 3.
    N. Isasti, D. Jorge-Badiola, M.L. Taheri, and P. Uranga: Metall. Mater. Trans. A, DOI:  10.1007/s11661-014-2450-7.
  4. 4.
    W. Schütz and F. Schröter: Mater. Sci. Technol., 2005, vol. 21, pp. 590–96.CrossRefGoogle Scholar
  5. 5.
    A. Ghosh, A. Ray, D. Chakrabarti, and C.L. Davis: Mater. Sci. Eng. A, 2013, vol. 561, pp. 126–35.CrossRefGoogle Scholar
  6. 6.
    V.S.A. Challa, W.H. Zhou, R.D.K. Misra, R. O’Malley, and S.G. Jansto: Mater. Sci. Eng. A, 2014, vol. 595, pp. 143–53.CrossRefGoogle Scholar
  7. 7.
    A. Iza-Mendia, and I. Gutiérrez: Mater. Sci. Eng. A, 2013, vol. 561, pp. 40–51.CrossRefGoogle Scholar
  8. 8.
    B. Wang, and J. Lian: Mater. Sci. Eng. A, 2014, vol. 592, pp. 50–56.CrossRefGoogle Scholar
  9. 9.
    J.M. Rodriguez-Ibabe: in The Making, Shaping and Treating of Steels, Flat Products Volume, AIST, 2014, pp. 113–170.Google Scholar
  10. 10.
    R. Zubialde, P. Uranga, B. López, and J.M. Rodriguez-Ibabe: in Proc. MS&T 2013 Conf., Montreal, 2013, pp. 313–20.Google Scholar
  11. 11.
    I. Gutiérrez: Mater. Sci. Eng. A, 2013, vol. 571, pp. 57–67.CrossRefGoogle Scholar
  12. 12.
    M.S. Bingley: Mater. Sci. Technol., 2001, vol. 17, pp. 700–14.Google Scholar
  13. 13.
    B. Mintz, G. Peterson, and A. Nassar: Ironmaking Steelmaking, 1994, vol. 21, pp. 215–22.Google Scholar
  14. 14.
    R.L. Higginson and C.M. Sellars: Worked Examples in Quantitative Metallography, The Institute of Materials, Minerals and Mining, London, 2003, pp. 1–116.Google Scholar
  15. 15.
    F.S. LePera: Metallography, 1979, vol. 12, pp. 263–8.CrossRefGoogle Scholar
  16. 16.
    K. Wallin: in ECOPRESS Research Seminar on Economical and Safe Application of Modern Steels for Pressure Vessels, Aachen, 2003.Google Scholar
  17. 17.
    P. Mohseni, J.K. Solberg, M. Karlsen, O.M. Akselsen, and E. Østby: Metall. Mater. Trans. A, 2014, vol. 45A, pp. 384–94.CrossRefGoogle Scholar
  18. 18.
    M.J. Merwin, C.T. Becker, and D.R. Giansante: in Proc. MS&T’09 Conf., Pittsburgh, (2009), pp. 956–68.Google Scholar
  19. 19.
    M. Díaz-Fuentes, A. Iza-Mendia, and I. Gutiérrez: Metall. Mater. Trans. A, 2003, vol. 34A, pp. 2505–16.CrossRefGoogle Scholar
  20. 20.
    N. Isasti, D. Jorge-Badiola, M.L. Taheri, B. López, and P. Uranga: Metall. Mater. Trans. A, 2011, vol. 42A, vol. 3729–42.Google Scholar
  21. 21.
    N. Isasti, D. Jorge-Badiola, M.L. Taheri, and P. Uranga: Metall. Mater. Trans. A, 2013, vol. 44A, pp. 3552–63.CrossRefGoogle Scholar
  22. 22.
    A. Fröm, and R. Sandstrom: Mater. Charact., 1999, vol. 41, pp. 111–22.CrossRefGoogle Scholar
  23. 23.
    T. Hanamura, F. Yin, and K. Nagai: ISIJ Int., 2004, vol. 44, pp. 610–7.CrossRefGoogle Scholar
  24. 24.
    W.B. Lee, S.G. Hong, C.G. Park, and S.H. Park: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 1689–98.CrossRefGoogle Scholar
  25. 25.
    P. Uranga, A.I. Fernández, B. López, and J.M. Rodriguez-Ibabe: in Proc. 43rd Mech. Working Steel Processing Conf., ISS, Warrendale, 2001, pp. 511–29.Google Scholar
  26. 26.
    M. Olasolo, P. Uranga, J.M. Rodriguez-Ibabe, and B. López: Mater. Sci. Eng. A, 2011, vol. 528, pp. 2559–69.CrossRefGoogle Scholar
  27. 27.
    N. Isasti: PhD Thesis, Tecnun (University of Navarra), San Sebastian, 2013.Google Scholar
  28. 28.
    Y.M. Kim, S.Y. Shin, H. Lee, B. Hwang, S. Lee, and N.J. Kim: Metall. Mater. Trans. A, 2007 vol. 38A, pp. 1731–42.CrossRefGoogle Scholar
  29. 29.
    X.Z. Zhang, and J.F. Knott: Acta Mater., 1999, vol. 47, pp. 3483–95.CrossRefGoogle Scholar
  30. 30.
    S.Y. Han, S.Y. Shin, S. Lee, N.J. Kim, J.H. Bae, and K. Kim: Metall. Mater. Trans. A, 2010, vol. 41A, pp. 329–40.CrossRefGoogle Scholar
  31. 31.
    J. Majta, R. Kuziak, M. Pietrzyk, and H. Krzton: J. Mater. Proc. Technol., 1996, vol. 60, pp. 581–88.CrossRefGoogle Scholar
  32. 32.
    B. Mintz, W.B. Morrison, and A. Jones: Met. Technol., 1979, vol. 6, pp. 252–60.CrossRefGoogle Scholar
  33. 33.
    F.B. Pickering and T. Gladman: Metallurgical Developments in Carbon Steels, Iron and Steel Inst., London, 1963, Special Report No. 81.Google Scholar
  34. 34.
    N. Isasti, D. Jorge-Badiola, M.L. Taheri, and P. Uranga: Met. Mater. Int., 2014 (in press).Google Scholar
  35. 35.
    B. Mintz: Metall. Mater. Trans. A, 1997, vol. 28A, pp. 1997–2073.Google Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2014

Authors and Affiliations

  • Nerea Isasti
    • 1
  • Denis Jorge-Badiola
    • 1
  • Mitra L. Taheri
    • 2
  • Pello Uranga
    • 1
  1. 1.CEIT and TECNUN (University of Navarra)Donostia-San SebastiánSpain
  2. 2.Department of Materials ScienceDrexel UniversityPhiladelphiaUSA

Personalised recommendations