Abstract
Intersections of shear bands in metastable austenites have been shown to be effective sites for strain-induced martensitic nucleation. The shear bands may be in the form of ε’ (hcp) martensite, mechanical twins, or dense bundles of stacking faults. Assuming that shear-band intersection is the dominant mechanism of strain-induced nucleation, an expression for the volume fraction of martensite vs plastic strain is derived by considering the course of shear-band formation, the probability of shear-band intersections, and the probability of an intersection generating a martensitic embryo. The resulting transformation curve has a sigmoidal shape and, in general, approaches saturation below 100 pct. The saturation value and rate of approach to saturation are determined by two temperature-dependent parameters related to the fee-bee chemical driving force and austenite stacking-fault energy. Fitting the expression to available data on 304 stainless steels gives good agreement for the shape of individual transformation curves as well as the temperature dependence of the derived parameters. It is concluded that the temperature dependence of the transformation kinetics (an important problem in the development of TRIP steels) may be minimized by decreasing the fee, bec, and hep entropy differences through proper compositional control.
Similar content being viewed by others
References
V. F. Zackay, E. R. Parker, D. Fahr, and R. Busch:Trans. ASM, 1967, vol. 60, p. 252.
M. Azrin, G. B. Olson, and R. A. Gagne: Department of the Army Technical Report, AMMRC TR 73-12, March 1973.
T. Angel:J. Iron Steel Inst., 1954, vol. 177, p. 165.
W. W. Gerberich, G. Thomas, E. R. Parker, and V. F. Zackay:Proc. Second Int. Conf. on the Strength of Metals and Alloys, p. 894, Asilomar, California, August 1970.
G. W. Powell, E. R. Marshall, and W. A. Backofen:Trans. ASM, 1958, vol. 50, p. 479.
F. Lecroisey and A. Pineau:Met. Trans., 1972, vol. 3, p. 387.
G. F. Boiling and R. H. Richman:Scri. Met, 1970, vol. 4, p. 539.
J. A. Venables:Phil. Mag., 1964, vol. 7, p. 35.
R. Lagneborg:.Acta Met., 1964, vol. 12, p. 823.
P. L. Manganon and G. Thomas:Met. Trans., 1970, vol. l, p. 1577.
G. B. Olson and M. Cohen:J. Less-Common Metals, 1972, vol. 28, p. 107.
C. J. Guntner and R.P. Reed:Trans. ASM, 1962, vol. 55, p. 399.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Olson, G.B., Cohen, M. Kinetics of strain-induced martensitic nucleation. Metall Trans A 6, 791–795 (1975). https://doi.org/10.1007/BF02672301
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02672301