Metallurgical and Materials Transactions A

, Volume 50, Issue 10, pp 4582–4593 | Cite as

The Role of Thermomechanical Processing in Creep Deformation Behavior of Modified 9Cr-1Mo Steel

  • P. Shruti
  • T. SakthivelEmail author
  • G. V. S. Nageswara Rao
  • K. Laha
  • T. Srinivasa Rao


In this study, to refine the microstructure and enhance the mechanical properties, thermomechanical treatment (TMT) was performed on modified 9Cr-1Mo steel. The creep deformation behavior of TMT processed steel and the steel in its normalized and tempered (NT) state were studied for different stress levels at 923 K (650 °C). Transient, secondary, and tertiary creep regimes were analyzed for both conditions of the steel based on the empirical equation \( \varepsilon = \varepsilon_{0} + \varepsilon_{\text{t}} \left( {1 - e^{ - rt} } \right) + \varepsilon_{\text{s}}^{ \cdot } t + \varepsilon_{\text{L}} e^{{p\left( {t_{\text{t}} - t_{\text{r}} } \right)}} \). The rate of exhaustion of primary creep (r), r with time to reach the minimum creep rate, minimum creep rate\( \left( {\varepsilon_{ \hbox{min} }^{ \cdot } } \right) \), \( \varepsilon_{ \hbox{min} }^{ \cdot } \) with time spent in the secondary creep regime, rate of acceleration of tertiary creep (p), p with time to reach the onset of tertiary creep, and creep rate with applied stress exhibited a proportional relationship in both conditions of the steel. This proportionality existence in the transient and tertiary creep deformation obeyed the first-order reaction rate kinetic theory. The enhanced MX (M = V, Nb; X = C, N) precipitation in the TMT steel significantly decreased the creep deformation rate and extended the secondary stages of deformation. TMT processing of modified 9Cr-1Mo steel led to a significant increase in the creep rupture strength through the stable microstructure.



The authors wish to thank Dr. A. K. Bhaduri, Director, Indira Gandhi Centre for Atomic Research, Kalpakkam, for his keen interest in the work and encouragement. The authors acknowledge the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE), Government of India, for providing financial support (Project No. 36(2)/14/42/2014-BRNS) to carry out this work. The authors also acknowledge Dr. N. Srinivasan, Head, Metal Working Group, DMRL, Hyderabad, for extending the hot-rolling facility.


  1. 1.
    K. Maruyama, K. Sawada, and J. Koike: Iron Steel Inst. Jpn. Int., 2001, vol. 41, pp. 641–53.CrossRefGoogle Scholar
  2. 2.
    L. Tan, J.T. Busby, P.J. Maziasz, and Y. Yamamoto: J. Nucl. Mater., 2013, vol. 441, pp. 713–17.CrossRefGoogle Scholar
  3. 3.
    R.L. Klueh, N. Hashimoto, and P.J. Maziasz: J. Nucl. Mater., 2007, vols. 367–370, pp. 48–53.CrossRefGoogle Scholar
  4. 4.
    Abe F (2008) Sci. Technol. 9(2):15.Google Scholar
  5. 5.
    M. Song, C. Sun, Z. Fan, Y. Chen, R. Zhu, K.Y. Yu, K.T. Hartwig, H. Wang, and X. Zhang: Acta Mater., 2016, vol. 112, pp. 361–77.CrossRefGoogle Scholar
  6. 6.
    L. Tan, D.T. Hoelzer, J.T. Busby, M.A. Sokolov, and R.L. Klueh: J. Nucl. Mater., 2012, vol. 422, pp. 45–50.CrossRefGoogle Scholar
  7. 7.
    L. Tan, Y. Yang, and J.T. Busby: J. Nucl. Mater., 2013, vol. 442, pp. S13–S17.CrossRefGoogle Scholar
  8. 8.
    J. Pešička, R. Kužel, A. Dronhofer, and G. Eggeler: Acta Mater., 2003, vol. 51, pp. 4847–62.CrossRefGoogle Scholar
  9. 9.
    E. Cerri, E. Evangelista, S. Spigarelli, and P. Bianchi: Mater. Sci. Eng. A, 1998, vol. 245, pp. 285–92.CrossRefGoogle Scholar
  10. 10.
    K. Laha, K.S. Chandravathi, P. Parameswaran, K. B. S. Rao, and S.L. Mannan: Metall. Mater. Trans. A, 2007, vol. 38A, pp. 58–68CrossRefGoogle Scholar
  11. 11.
    Triratna Shrestha, Mehdi Basirat, Indrajit Charit, Gabriel P. Potirniche, and Karl K. Rink: Mater. Sci. Eng. A, 2013, vol. 565, pp. 382–91.CrossRefGoogle Scholar
  12. 12.
    S. Hollner, B. Fournier, J. Le Pendu, T. Cozzika, I. Tournié, J.-C. Brachet, and A. Pineau: J. Nucl. Mater., 2010, vol. 405, pp. 101–08.CrossRefGoogle Scholar
  13. 13.
    D.V.V. Satyanarayana, G. Malakondaiah, C. Phaniraj, and D.S. Sarma: Mater. Sci. Technol., 2009, vol. 25 (8), pp. 953–59.CrossRefGoogle Scholar
  14. 14.
    C. Phaniraj, M. Nandagopal, S.L. Mannan, and P. Rodriguez: Acta Metall. Mater., 1991, vol. 39 (7), pp. 1651–56.CrossRefGoogle Scholar
  15. 15.
    T.C. Totemeier, H. Tian, and J.A. Simpson: Metall. Mater. Trans. A, 2006, vol. 37A, pp. 1519–25.CrossRefGoogle Scholar
  16. 16.
    Sakthivel T, Shruti P, Parameswaran P, Rao GVSN, Laha K, and Rao TS (2016): Trans. Ind. Inst. Met., 1:23CrossRefGoogle Scholar
  17. 17.
    Irina Fedorova, Alla Kipelova, Andrey Belyakov, and Rustam Kaibyshev: Metall. Mater. Trans. A, 2013, vol. 44A, pp. 128–35.CrossRefGoogle Scholar
  18. 18.
    T. Sakthivel, S. P. Selvi, and K. Laha: Mater. Sci. Eng. A, 2015, vol. 640, pp. 61–71.CrossRefGoogle Scholar
  19. 19.
    P.G. McVetty: Mech. Eng., 1934, vol. 56, p. 149.Google Scholar
  20. 20.
    F. Garofalo: Fundamentals of Creep and Creep Rupture in Metals, Macmillan, New York, NY, 1965.Google Scholar
  21. 21.
    J.B. Conway: Numerical Methods for Creep and Rupture Analysis, Gordon & Breach, New York, NY, 1968.Google Scholar
  22. 22.
    J.B. Conway and M.J. Mullikin: Trans. TMS-AIME, 1966, 242, p. 1496.Google Scholar
  23. 23.
    W.J. Evans and B. Wilshire: Trans. TMS-AIME, 1968, 242, p. 2514.Google Scholar
  24. 24.
    G.A. Webster, A.P.D. Cox, and J.E. Dorn: Met. Sci. J., 1969, vol. 3, p. 221.CrossRefGoogle Scholar
  25. 25.
    P.W. Davies, W.J. Evans, K.R. Williams, and B. Wilshire: Scripta Metall., 1969, vol. 3, pp. 671–74.CrossRefGoogle Scholar
  26. 26.
    P.W. Davies and K.R. Williams: Acta Metall., 1969, vol. 17, pp. 897–903.CrossRefGoogle Scholar
  27. 27.
    F. Dobes and J. Cadek: Kov. Mater., 1981, vol. 19, p. 31.Google Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2019

Authors and Affiliations

  • P. Shruti
    • 1
  • T. Sakthivel
    • 2
    Email author
  • G. V. S. Nageswara Rao
    • 1
  • K. Laha
    • 2
  • T. Srinivasa Rao
    • 3
  1. 1.National Institute of TechnologyWarangalIndia
  2. 2.Indira Gandhi Centre for Atomic ResearchKalpakkamIndia
  3. 3.National Institute of TechnologyThiruchirapallyIndia

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