Abstract
The analytical electron microscope (AEM) was used to examine the microstructure of type 316LN stainless steel alloys which had been annealed for 50 to 300 hours in the temperature range 600 to 700 °C. The M23C6 carbide chemistry and distribution are described as a function of heat treatment.X-ray spectroscopy in the AEM revealed significant chromium depletion at grain boundaries in the vicinity of carbides for samples aged at 50 and 100 hours at 650 °C and 100 and 300 hours at 700 °C, with lower grain boundary chromium values observed at 650 °C than at 700 °C. The width of the chromium depleted zone normal to the grain boundaries increased with increasing annealing time and/or temperature. Measurements of chromium concentration along the grain boundaries away from a carbide were made after aging at 700 °C for 100 hours, and the chromium level rose steadily until the bulk value was reached at a distance of ~3μm from the carbide. The width of the chromium depleted zone normal to the boundaries in the same sample was an order of magnitude less. Some molybdenum depletion was also found at the grain boundaries, and the Mo-depletion profiles were in form and extent similar to the chromium results. Simple thermodynamic models were used to calculate the equilibrium value of chromium at the carbide-matrix interface, and the chromium distribution along and normal to the grain boundaries. The results of these models agreed well with the AEM results, and the agreement can be improved by considering the effect of electron probe configuration on the AEM measurements. The calculated thermodynamic data and the AEM results were related to the corrosion behavior of the alloys. The occurrence of severe asymmetries in some concentration profiles normal to the grain boundaries, which increased with increasing annealing temperature or time, was shown to be due to boundary movement during the discontinuous precipitation of M23C6 carbides.
Similar content being viewed by others
References
E. C. Bain, R. H. Aborn, and J. J. B. Rutherford:Trans. Amer. Steel Treating Society, 1933, vol. 21, pp. 481–509.
T.M. Devine:J. Electrochemical Soc, 1979, vol. 126, pp. 374–85.
R. L. Cowan, II, and G. M. Gorden:Proc. Conf. Stress Corr. Cracking and Hydrogen Embrittlement, NACE, Houston, TX, 1977, p. 1025.
K. Osozawa and H. J. Engeil:Corr. Sci., 1966, vol. 6, pp. 389–93.
W.O. Binder, CM. Brown, and R.H. Franks:Trans. ASM, 1949, vol. 41, pp. 1301–55.
M.L. Holzworth, F. H. Beck, and M. G. Fontana:Corrosion, 1951, vol. 7, pp. 441–49.
P. Chung and S. Sklarska-Smialowska:Corrosion, 1981, vol. 37, pp. 39–50.
C. L. Briant and A. M. Ritter:Metall. Trans. A, 1980, vol. 11A, pp. 2009–17.
C.L. Briant and A.M. Ritter:Scripta Met., 1979, vol. 13, pp. 177–81.
C. L. Briant:Res. Mechanica Letters, 1981, vol. 1, pp. 471–74.
V. Cihal: C.G. Akinov State Research Institute for the Protection of Materials, Prague, Czechoslovakia, unpublished research, 1969.
R.L. Fullman:Acta Metall., 1982, vol. 30, pp. 1407–15.
C.L. Briant, R. A. Mulford, and E. L. Hall:Corrosion, 1982, vol. 38, p. 468–77.
R.A. Mulford, E. L. Hall, and C.L. Briant:Corrosion, 1983, vol. 39, pp. 132–43.
C.L. Briant:Corrosion, 1980, vol. 36, pp. 497–509.
J.S. Armijo:Corrosion, 1968, vol. 24, pp. 24–30.
C. Stawstrom and M. Hillert:J. Iron Steel Inst., 1969, vol. 207, pp. 77–85.
C.S. Tedmon, Jr., D. A. Vermilyea, and J. H. Rosolowski:J. Electrochemical Soc, 1969, vol. 118, pp. 192–202.
C.S. Pande, M. Suenaga, B. Vyas, H.S. Isaacs, and D.F. Harling:Scripta Met., 1977, vol. 11, pp. 681–84.
E. L. Hall:Proc. 39th Annual Meeting, Electron Microscopy Society of America, G. W. Bailey, ed., Claitor’s, Baton Rouge, LA, 1981, p. 288.
E. L. Hall:Proc. 40th Annual Meeting, Electron Microscopy Society of America, G.W. Bailey, ed., Claitor’s, Baton Rouge, LA, 1982, p. 518.
M.G. Burke and E.P. Butler:ibid., pp. 514-15.
G. Cliff and G. W. Lorimer:J. Micros., 1975, vol. 103, pp. 203–07.
J.I. Goldstein and D.B. Williams:Quantitative Microanalysis with High Spatial Resolution, The Metals Society, London, 1981, p. 5.
J.I. Goldstein, J.L. Costley, G.W. Lorimer, and S.J.B. Reed:Scanning Electron Microscopy /1977/I, O. Johari, ed., Chicago Press, Chicago, IL, 1977, p. 315.
E. L. Hall, D. Imeson, and J. B. Vander Sande:Phil. Mag. A, 1981, vol. 43, pp. 1569–85.
E. L. Hall:Journal de Physique, 1982, Colloque C6, Supplement No. 12, vol. 43, pp. C6239-C6254.
M.H. Lewis and B. Hattersley:Acta Metall., 1965, vol. 13, pp. 1159–68.
L.K. Singhal and J.W. Martin:Trans. TMS-AIME, 1968, vol. 242, pp. 814–19.
C. DeCasa, V. B. Nileshwar, and D. A. Melford:J. Iron Steel Inst., 1969, vol. 207, pp. 1325–32.
B. Weiss and R. Stickler:Metall. Trans., 1972, vol. 3, pp. 851–66.
P. D. Southwick and R. W. K. Honeycombe:Metal Science, 1982, vol. 16, pp. 475–81.
R.J. Bendure, L. C. Ikenberry, and J.H. Waxweiler:Trans. TMS-AIME, 1961, vol. 221, pp. 1032–39.
K. Natesan and T. F. Kassner:Metall. Trans., 1975, vol. 4, pp. 2557–66.
Bjorn Urenius:Scand. J. Metallurgy, 1977, vol. 6, pp. 7–13.
F. D. Richardson:J. Iron Steel Inst., 1953, vol. 175, pp. 33–51.
C. Zener:J. Appl. Phys., 1949, vol. 20, pp. 950–53.
F.C. Frank:Proc. Roy. Soc. A, 1950, vol. 201, pp. 586–99.
F.S. Ham:Quart. J. Appl. Math., 1959, vol. 17, pp. 137–45.
J. W. Christian:The Theory of Transformations in Metals and Alloys, p. 440, Pergamon Press, Oxford, 1965, p. 440.
R.L. Fullman:Proc. Seminar in Countermeasures for Pipe Cracking in BWRs, paper 26, EPRI, Palo Alto, CA, 1980.
A.D. Brailsford and H.B. Aaron:J. Appl. Phys., 1969, vol. 40, pp. 1702–10.
P.G. Shewmon:J. Appl. Phys., 1965, vol. 34, pp. 755–57.
J.H. Rosolowski:Metall. Trans., 1972, vol. 3, pp. 285–90.
P. Duhaj, J. Ivan, and E. Makovicky:J. Iron Steel Inst., 1968, vol. 206, pp. 1245–51.
U. E. Wolff:Trans. TMS-AIME, 1966, vol. 236, pp. 19–27.
F.R. Backitt and B.R. Clark:Acta Metall., 1967, vol. 15,pp. 113–29.
K.N. Tu and D. Turnbull:Acta Metall., 1967, vol. 15, pp. 369–76.
R.A. Fournelle and J.B. Clark:Metall. Trans., 1972, vol. 3, pp. 2757–67.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hall, E.L., Briant, C.L. Chromium depletion in the vicinity of carbides in sensitized austenitic stainless steels. Metall Trans A 15, 793–811 (1984). https://doi.org/10.1007/BF02644554
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02644554