The Incomplete Bainite Reaction: Possible Reasons for Apparent Differences in TEM and Atom-Probe Determination of Austenite Carbon Content

D. Hall, H. K. D. H. Bhadeshia and W. Stobbs

Abstract

Carbon segregation following the transformation of 0.43C-2.02Si-3Mn and 0.39C-2.05Si-4.09Ni wt.% steels to bainite has been studied by both atom probe and TEM lattice fringe techniques. The inferred carbon concentrations in the retained austenite are in general agreement with the theory that bainitic ferrite grows with the parent austenite carbon content (i.e. fully-supersaturated). However, "indirect" lattice fringe measurements suggest a broader spread for the carbon contents than the "direct" atom probe results. In this paper we present further confirmatory data using the former approach and investigate the possible causes for the apparent inconsistency between the techniques. In particular, we consider in detail the effect of the retained constrained elastic strains, associated with the transformation, on the TEM results.

Journal de Physique, Colloque C4, No. 12, Vol. 43, 1982, pp. C4-449-454.

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