Metallurgical Transactions A

, Volume 23, Issue 10, pp 2849–2857

Processing map for controlling microstructure in hot working of hot isostatically pressed powder metallurgy NIMONIC AP-1 superalloy

  • M. C. Somani
  • E. S. Bhagiradha Rao
  • N. C. Birla
  • M. L. Bhatia
  • Vakil Singh
  • Y. V. R. K. Prasad
Mechanical Behavior

Abstract

The hot deformation behavior of hot isostatically pressed (HIP) NIMONIC AP-1 superalloy is characterized using processing maps in the temperature range 950 °C to 1200 °C and strain rate range 0.001 to 100 s•1. The dynamic materials model has been used for developing the pro-cessing maps which show the variation of the efficiency of power dissipation given by [2m/ (m + 1)] with temperature and strain rate, withm being the strain rate sensitivity of flow stress. The processing map revealed a domain of dynamic recrystallization with a peak efficiency of 40 pct at 1125 °C and 0.3 s•1, and these are the optimum parameters for hot working. The microstructure developed under these conditions is free from prior particle boundary (PPB) de-fects, cracks, or localized shear bands. At 100 s•1 and 1200 °C, the material exhibits inter-crystalline cracking, while at 0.001 s•1, the material shows wedge cracks at 1200 °C and PPB cracking at 1000 °C. Also at strain rates higher than 10 s•1, adiabatic shear bands occur; the limiting conditions for this flow instability are accurately predicted by a continuum criterion based on the principles of irreversible thermodynamics of large plastic flow.

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References

  1. 1.
    C.H. Symonds, J.W. Eggar, G.J. Lewis, and R.J. Siddall:Powder Metall. Int., 1983, vol. 15, pp. 30–35.Google Scholar
  2. 2.
    T.L. Prakash, M.C. Somani, and E.S. Bhagiradha Rao:Key Eng. Mater., 1989, vol. 29-31, pp. 179–98.Google Scholar
  3. 3.
    T.L. Prakash, Y.N. Chari, E.S. Bhagiradha Rao, and R. Thamburaj:Metall. Trans. A, 1983, vol. 14A, pp. 733–42.Google Scholar
  4. 4.
    R. Thamburaj, W. Wallace, Y.N. Chari, and T.L. Prakash:Powder Metall., 1984, vol. 27, pp. 169–80.Google Scholar
  5. 5.
    J.K. Chakravartty, M.K. Asundi, and Y.V.R.K. Prasad:Metall. Trans. A, 1991, vol. 22A, pp. 829–36.Google Scholar
  6. 6.
    N. Ravichandran and Y.V.R.K. Prasad:Metall. Trans. A, 1991, vol. 22A, pp. 2339–48.Google Scholar
  7. 7.
    Y.V.R.K. Prasad, H.L. Gegel, S.M. Doraivelu, J.C. Malas, J.T. Morgan, K.A. Lark, and D.R. Barker:Metall. Trans. A, 1984, vol. 15A, pp. 1883–92.Google Scholar
  8. 8.
    H.L. Gegel, J.C. Malas, S.M. Doraivelu, and V.A. Shende:Metals Handbook, ASM, Metals Park, OH, 1987, vol. 14, pp. 417–38.Google Scholar
  9. 9.
    J.M. Alexander: inModeling of Hot Deformation of Steels, J.G. Lenard, ed., Springer-Verlag, Berlin, 1984, pp. 101–15.Google Scholar
  10. 10.
    H. Ziegler:Progress in Solid Mechanics, John Wiley and Sons, New York, NY, 1963, vol. 4, pp. 93–193.Google Scholar
  11. 11.
    A.K.S. Kalyan Kumar: M.S. Thesis, Indian Institute of Science, Bangalore, India, 1987.Google Scholar
  12. 12.
    Y.V.R.K. Prasad:Ind. J. Technol, 1990, vol. 28, pp. 435–51.Google Scholar
  13. 13.
    R. Thamburaj, A.K. Koul, W. Wallace, and M.C. de Malherbe:Modern Developments in Powder Metallurgy, E.N. Aque and C.I. Whitman, eds., Metal Powder Industries Federation, Princeton, NJ, 1985, vol. 16, pp. 635–72.Google Scholar
  14. 14.
    J.S. Crompton and R.W. Hertzberg:J. Mater. Sci., 1986, vol. 21, pp. 3445–53.CrossRefGoogle Scholar
  15. 15.
    C. Marquez, G. L’Esperance, and A.K. Koul:Int. J. Powder Metall., 1989, vol. 25, pp. 301–08.Google Scholar
  16. 16.
    R. Raj:Metall. Trans. A, 1981, vol. 12A, pp. 1089–97.Google Scholar
  17. 17.
    T.W. Allen and L.J. Cartmell:J. Inst. Met., 1968, vol. 96, pp. 321–29.Google Scholar
  18. 18.
    P.A. Tibbits and J.R. Becker: Report No. 2CLR 557, Cameron Iron Works Inc., Houston, TX, 1982.Google Scholar

Copyright information

© The Minerals, Metals and Materials Society, and ASM International 1992

Authors and Affiliations

  • M. C. Somani
    • 1
  • E. S. Bhagiradha Rao
    • 1
  • N. C. Birla
    • 1
  • M. L. Bhatia
    • 1
  • Vakil Singh
    • 2
  • Y. V. R. K. Prasad
    • 3
  1. 1.Defence Metallurgical Research LaboratoryHyderabadIndia
  2. 2.Department of Metallurgical EngineeringBanaras Hindu UniversityVaranasiIndia
  3. 3.Department of MetallurgyIndian Institute of ScienceBangaloreIndia

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