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Metallurgical stability and the fracture behavior of ferritic stainless steels

  • C. H. Chun
  • D. H. Polonis
Processing
  • 99 Downloads

Abstract

The influence of aluminum on the thermal stability of ferritic stainless steels has been investigated using two commercial alloys— Armco Type 18SR and AISI430. Two reaction stages have been detected in these alloys during aging at 475 °; each stage is accompanied by changes in the hardness, yield strength, strain-hardening exponent, and elongation to fracture. The initial stage is attributed to the precipitation of carbide and nitride particles and the second stage to the precipitation of the chromium- rich a’ phase. The 430 alloy exhibits more pronounced changes than 18SR during the first stage due to the higher concentration of interstitials retained in solution after quenching. The effects of the second- stage aging reaction are detected after shorter aging times in the 18SR alloy and are more pronounced than in the 430 alloy, consistent with the influence of aluminum on the coherency strains associated with a’ precipitation. The fracture mechanism in both alloys changes from ductile dimples in the solution- treated and quenched condition to a mix of ductile dimples, intergranular fracture, and transgranular cleavage with increased aging times. Longitudinal cracking at the grain boundaries precedes failure of the aged alloys in tension; it is attributed to the combined effects of void initiation at fine grain boundary precipitates, a’ embrittlement that limits localized plasticity, and the transverse stress components resulting from triaxiality after the onset of necking.

Keywords

Yield Strength Aging Time Intergranular Fracture Ferritic Stainless Steel Intergranular Crack 
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.

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References

  1. 1.
    R.M. Fisher, E.J. Dulis, and K.G. Carroll,Trans. AIME, 197, 690–695(1953).Google Scholar
  2. 2.
    R.O. Williams and H.W. Paxton,J. Iron Steel Inst., London, 185, 358–374(1957).Google Scholar
  3. 3.
    M.J. Blackburn and J. Nutting,J. Iron Steel Inst., London, 202, 610–613(1964).Google Scholar
  4. 4.
    O. Kubaschewski and T.G. Chart,J. Inst. Metals, 93, 329–338 (1964–65).Google Scholar
  5. 5.
    M.J. Marcinkowski, R.M. Fisher, and A. Szirmae,Trans. AIME, 2J0, 676–689(1964).Google Scholar
  6. 6.
    R. Lagneberg,Trans. ASM, 60,67–78 (1967).Google Scholar
  7. 7.
    T.De Nye and P.M. Gehlen,Met. Trans., 2,1423–1428 (1971).Google Scholar
  8. 8.
    D. Chandra and L.H. Schwartz,Met. Trans., 2, 511–519 (1971).CrossRefGoogle Scholar
  9. 9.
    W.O. Binder and H.R. Spendelow,Trans. ASM, 43, 759–772 (1951).Google Scholar
  10. 10.
    A. Plumtree and R. Gullberg,Met.Trans., 7/l, 1451–1458 (1976).CrossRefGoogle Scholar
  11. 11.
    W.S. Spear, Ph.D. dissertation, University of Washington (1987).Google Scholar
  12. 12.
    R.A. Perkins, “Materials for Coal Conversion and Utilization,” Energy Research and Development Association, Conference, Gaithersburg, Maryland, 77–1025, 11–26, Oct (1977).Google Scholar
  13. 13.
    H. Ishii and Y. Hujimura,J.Jpn.Inst. Metals, 39, 311–317 (1975).CrossRefGoogle Scholar
  14. 14.
    H. Thielsch,Welding J., 34, 225 (1955).Google Scholar
  15. 15.
    J.J.Demo,Corrosion, 27(12), 531 (1971).CrossRefGoogle Scholar
  16. 16.
    K. Woltron.Berg Huttenmaennische Monatsch., 116, 429 (1972).Google Scholar
  17. 17.
    R.N. Wright, “Toughness of Ferritic Stainless Steels,” ASTM STP706, R.A. Lula, Ed., ASTM, Philadelphia, 2–33 (1980).CrossRefGoogle Scholar
  18. 18.
    T.J. Nichol, A. Datta, and G. Aggen,Met. Trans., 11A, 573–585 (1980).CrossRefGoogle Scholar
  19. 19.
    G. Aggen, H.E. Edeverell, and T.J. Nichol, “Micon 78,” ASTM STP 672, 334–369(1979).Google Scholar
  20. 20.
    A.W. Thompson and J.C. Williams,Fracture 1977, Vol. 2A, ICF4, Waterloo, Canada, 343–348 (1974).Google Scholar
  21. 21.
    I.M. Wolff and A. Ball,Acta Metall. Mater., 39(11), 2759–2770 (1991).CrossRefGoogle Scholar
  22. 22.
    J.C. Williams, R.R. Boyer, and M.J. Blackburn, “Electron Mi- crofractography,” ASTM STP 453, ASTM, Philadelphia, 215- 235 (1968).Google Scholar
  23. 23.
    T.J. Nichol,Met. Trans., 8A, 229–237 (1977).CrossRefGoogle Scholar
  24. 24.
    P. Koutanieni, V. Heikkeinen, and A. Saarinen,Metal Sci., 8, 94- 96(1974).CrossRefGoogle Scholar
  25. 25.
    B.J. Grobner, Report No. RP-33-71-02, Climax Molybdenum Co., Jan (1974).Google Scholar
  26. 26.
    T. Yasunaka,Trans. Nat. Res. Inst. Met., 22(3), 10–18(1980).Google Scholar
  27. 27.
    J.F. Grubb, R.N. Wright, and P. Farrar, “Toughness of Ferritic Stainless Steels,” ASTM STP 706, R.A. Lula, Ed., ASTM, Phila- delphia, 56–76 (1980).CrossRefGoogle Scholar
  28. 28.
    A.I. Kondyr, A.N. Tkach, V.I. Atashkin, and M. Zamora,Fiz. Khim. Mekh. Mater., 10,24–28 (1974).Google Scholar
  29. 29.
    Y. Imai, K. Nishino, and Y. Nakagawa.J. Jpn. Inst. Metals, 29(4), 346–350(1965).CrossRefGoogle Scholar
  30. 30.
    T. Yasunaka and M. Kanao,Transactions of the Iron and Steel Institute of Japan, 19, 69–75 (1979).CrossRefGoogle Scholar
  31. 31.
    G.G. Garrett and J.F. Knott,Met. Trans., 9A, 1187–1201 (1978).CrossRefGoogle Scholar
  32. 32.
    A. Nadai,Theory of Flow and Fracture of Solids, McGraw-Hill, New York (1950).Google Scholar

Copyright information

© ASM International 1992

Authors and Affiliations

  • C. H. Chun
    • 1
  • D. H. Polonis
    • 1
  1. 1.Department of Materials Science and EngineeringUniversity of WashingtonSeattle

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