A model steel (Fe-W-C) has been used to study the effect of the precipitation of carbides at austenite grain surfaces, on the subsequent formation of allotriomorphic ferrite. It is found that the removal of potent austenite grain boundary nucleation sites by the precipitation of carbides retards the allotriomorphic ferrite transformation. This effect is found to be most pronounced at small undercoolings below the equilibrium transformation temperature. At larger undercoolings where nucleation is not as much of a rate-limiting factor, the depletion of solute from the austenite, due to carbide precipitation, results in an acceleration of ferrite formation.
Materials Science and Engineering A, Vol. A157, 1992, pp. 101-106.
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