Kinetics of the Widmanstatten Ferrite Transformation in Steels

S. J. Jones and H. K. D. H. Bhadeshia


Widmanstatten ferrite grows by a paraequilibrium displacive mechanism but it rarely occurs in isolation in steels. It is usually preceded by a reconstructive transformation mechanism. In this paper, we deal with a novel modification of the Avrami overall transformation kinetics theory as adapted by Cahn, for grain boundary nucleated phases. Our modification deals with the simultaneous occurrence of two or more transformations. The method is demonstrated to faithfully reproduce published data on the volume fractions of allotriomorphic and Widmanstatten ferrite as a function of chemical composition, austenite grain size and heat treatment (isothermal or continuous cooling transformation).

Displacive Phase Transformations and their Applications in Materials Engineering, eds K. Inoue, K. Mukherjee, K. Otsuka and H. Chen, The Minerals, Metals and Materials Society, Warrendale, Pennsylvania, U.S.A., (1998) 419-426.

Computer programs associated with this paper can be obtained from the Materials Algorithms Project

Widmanstatten ferrite

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