Abstract
The statistical-mechanics of a generalized perfect lattice gas is used to describe the distribution of interstitial solute atoms in martensite. In untempered martensite, partitioning of mobile interstitial carbon occurs between normal octahedral interstitial sites and those distorted sites around immobile dislocations. The statistics adopted acknowledge the finite number of each kind of site per unit volume of martensite. The dislocation density, fraction of twinned martensite, and the arrangement of dislocations are all input variables in the calculations. The principal quantities calculated are the fraction of carbon atoms segregated to dislocations and the fraction of distorted sites occupied as functions of the carbon content and substructure. The equilibrium distribution of carbon is also determined for tempering conditions where either ∈-carbide or cementite may precipitate. Here, the change in the solubility limit of ferrite with dislocation density is predicted. In untempered low carbon martensites (at 300°K) 85 pct of the carbon will be segregated to dislocations at equilibrium. This value decreases to 60 pct in an 0.80 wt pct C steel. Less than 5 pct of the distorted sites are filled when the dislocation distribution is uniform. Much higher concentrations occur when the long range stresses of the dislocations are relaxed and the mean carbon/dislocation interaction energy increases. Analogous results are presented for the equilibrium among carbides, normal sites, and distorted sites. The predictions of the lattice gas model are in agreement with numerous independent experimental observations.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
R. H. Fowler:Statistical Mechanics, Cambridge Univ. Press, London, 1936.
J. H. van der Waals and J. C. Platteeuw:Advances in Chemical Physics, Vol.II, Chap. 1, Interscience Publ., Inc., New York, 1959.
A. W. Cochardt, G. Schoek, and H. Wiedersich:Acta Met., 1955, vol. 3, p. 533.
R. Chang:Fundamental Aspects of Dislocation Theory, Nat. Bur. Stand. Spec. Publ. 317, 1970.
David Kalish and Morris Cohen: IMD Symp. onStrength and Deformation of Martensite, May 5, 1969, Pittsburgh Pa.; Lockheed-Georgia Company Research Memorandum, ER-11028, 1971.
H. D. Soloman and C. J. McMahon, Jr.:Work Hardening, p. 311, Gordon and Breach Science Publ., New York, 1968.
G. R. Speich:Trans. TMS-AIME, 1969, vol. 245, p. 2553. (b) G. R. Speich: U.S. Steel Corp., Research Center, Monroeville, Pa., private communication, 1969.
J. M. Genin and P. A. Flinn:Trans. TMS-AIME, 1968, vol. 242, p. 1419.
J. C. Swartz:Mater. Sci. Eng., 1969–70, vol. 5, p. 30.
David Kalish and Morris Cohen:Mater. Sci. Eng., 1970, vol. 6, p. 156.
Morris Cohen:Proc. of the Intern. Conf. on the Strength of Metals and Alloys, Tokyo, 1967, Suppl. toTrans. JIM, 1968, vol. 9, p. xxiii.
J. P. Hirth and J. Lothe:Theory of Dislocations, Chap. 14, McGraw-Hill Book Co., New York, 1968.
D. V. Wilson:Acta Met., 1955, vol. 5, p. 293.
B. A. MacDonald: Ph.D. Thesis, M.I.T., Cambridge, Mass., 1964.
C. J. Barton:Acta Met., 1969, vol. 17, p. 1085.
R. A. Arndt and A. C. Damask:Acta Met., 1964, vol. 12, p. 341.
L. Darken and R. Gurry:Physical Chemistry of Metals, McGraw Hill, New York, 1953.
G. Langford and Morris Cohen:Trans. ASM, 1969, vol. 62, p. 623.
H. J. Rack and Morris Cohen:Mater. Sci. Eng., 1970, vol. 6, p. 320.
M. L. Rudee and R. A. Huggins:Acta Met., 1964, vol. 12, p. 501.
Author information
Authors and Affiliations
Additional information
David Kalish, formerly withLockheed-Georgia Co.
E. M. Roberts, formerly with Lockheed-Georgia Co.
Rights and permissions
About this article
Cite this article
Kalish, D., Roberts, E.M. On the distribution of carbon in martensite. Metall Trans 2, 2783–2790 (1971). https://doi.org/10.1007/BF02813252
Issue Date:
DOI: https://doi.org/10.1007/BF02813252