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Microstructural evolution of modified 9Cr-1Mo steel

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Abstract

The tempering and subsequent annealing of modified 9Cr-lMo steel have been investigated to determine the influence of trace amounts of V and Nb on the sequence of precipitation processes and to identify the basis for the enhanced high-temperature strength compared to the standard 9Cr-lMo composition. Air cooling (normalizing) from 1045 °C results in the precipitation of fine (Fe, Cr)3C particles within the martensite laths. Additional carbide precipitation and changes in the dislocation structure occur during the tempering of martensite at 700 °C and 760 °C after normalizing. The precipitation of M23C6 carbides occurs preferentially at lath interfaces and dislocations. The formation of Cr2C was detected during the first hour of tempering over the range of 650 °C to 760 °C but was replaced by V4C3 within 1 hour at 760 °C. During prolonged annealing at 550 °C to 650 °C, following tempering, the lath morphology remains relatively stable; partitioning of the laths into subgrains and some carbide coarsening are evident after 400 hours of annealing at 650 °C, but the lath morphology persists. The enhanced martensite lath stability is attributed primarily to the V4C3 precipitates distributed along the lath interfaces and is suggested as the basis for the improved performance of the modified 9Cr-lMo alloy under elevated temperature tensile and creep conditions.

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References

  1. M.K. Booker, V.K. Sikka, and B.L.P. Booker:Proc. ASM INTERNATIONAL Conf. on Ferritic Steels for High Temperature Applications, Warrendale, PA, Oct. 6-8, 1981, Ashok K. Khare, ed., ASM, Metals Park, OH, pp. 257–73.

    Google Scholar 

  2. Vinod K. Sikka:Proc. Topical Conf. on Ferritic Alloys for Use in Nuclear Energy Technologies, J.W. Davis and D.J. Michel, eds., TMS-AIME, Warrendale, PA, 1984, pp. 317–27.

    Google Scholar 

  3. Wendell B. Jones:Proc. ASM INTERNATIONAL Conf. on Ferritic Steels for High Temperature Applications, Warrendale, PA, Oct. 6-8, 1981, Ashok K. Khare, ed., ASM, Metals Park, OH, pp. 221–35.

    Google Scholar 

  4. V.K. Sikka, M.G. Cowgill, and B.W. Roberts:Proc. Topical Conf. on Ferritic Alloys for Use in Nuclear Energy Technologies, J.W. Davis and D.J. Michel, eds., TMS-AIME, Warrendale, PA, 1984, pp. 413–23.

    Google Scholar 

  5. G. Ebi and A.J. McEvily:Fatigue Eng. Mater. Struct., 1984, vol. 7 (4), pp. 299–314.

    Article  Google Scholar 

  6. A.J. McEvily and J. Bunch: Final Technical Report, July 1, 1982- June 30, 1984, Report No. DE85012309/WMS, Apr. 29, 1985, p. 34.

  7. R.W.K. Honeycombe: inISI Special Report 86, Joint BISRA- ISI Conf., Scarborough, United Kingdom, June 2-4, 1964.

  8. F.B. Pickering:Physical Metallurgy and the Design of Steels, Applied Science Publishers Ltd., London, 1978, p. 136.

    Google Scholar 

  9. E. Tekin and P.M. Kelly:Precipitation from Iron Base Alloys, TMS Conf. No. 28, Gordon and Breach, New York, NY, 1963,. p. 173.

    Google Scholar 

  10. S.J. Sanderson:Proc. ASM INTERNATIONAL Conf. on Ferritic Steels for High Temperature Applications, Warrendale, PA, Oct. 6-8, 1981, Ashok K. Khare, ed., ASM, Metals Park, OH, pp. 85–99.

    Google Scholar 

  11. J. Nutting:J. Iron Steel Inst., 1969, vol. 207, pp. 872–93.

    CAS  Google Scholar 

  12. K.J. Irvine and F.B. Pickering:J. Iron Steel Inst., 1960, vol. 194, pp. 137–53.

    CAS  Google Scholar 

  13. J. Nutting:Proc. Topical Conf. on Ferritic Alloys for Use in Nuclear Energy Technologies, J.W. Davis and D.J. Michel, eds.,TMS-AIME, Warrendale, PA, 1984, pp. 3–16.

    Google Scholar 

  14. E. Smith and J. Nutting:J. Iron Steel Inst., 1957, vol. 187, pp. 314–29.

    CAS  Google Scholar 

  15. R.W.K. Honeycombe, H.J. Harding, and J.T. Irani:inHigh Strength Materials, V.F. Zakay, ed., John Wiley, New York, NY, 1965, pp. 230–50.

    Google Scholar 

  16. N.K. Balliger and R.W.K. Honeycombe:Met. Sci., 1980, pp. 121–33.

  17. B.B. Argent, M.N. van Niekerk, and G.A. Redfern:J. Iron Steel Inst., 1970, pp. 830–43.

  18. R.D. Leapman, S.J. Sanderson, and M.J. Whelan:Met. Sci., 1978, pp. 215–20.

  19. R.S. Fidler: Laboratory Note No. RD/L/N 9/77, Central Electricity Research Laboratories, Leatherhead, Surrey, United Kingdom, Jan. 1977.

  20. W.C. Leslie:The Physical Metallurgy of Steels, Hemisphere Publishing Corp., McGraw-Hill Book Co., New York, NY, 1981.

    Google Scholar 

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Jones, W.B., Hills, C.R. & Polonis, D.H. Microstructural evolution of modified 9Cr-1Mo steel. Metall Trans A 22, 1049–1058 (1991). https://doi.org/10.1007/BF02661098

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