THE BAINITE TRANSFORMATION IN CHEMICALLY HETEROGENEOUS 300M HIGH-STRENGTH STEEL

A theoretical model of the bainite reaction in chemically heterogeneous steels is compared with experimental data obtained using commercially available 300M ultrahigh-strength steel. It is demonstrated that the development of microstructure is influenced strongly by variations in substitutional solute concentrations. The maximum degree of transformation to bainite at any given transformation temperature was, in general, higher for homogenized samples than for the steel in the as-received, segregated condition. The results are analyzed using a computer model in which the heterogeneous steel is represented in terms of a series of slices, each of a different, but uniform, composition. The transformation was allowed to proceed in each slice, both in circumstances where the slices did not interact and when carbon was allowed to redistribute between the slices. The model is found to be a good quantitative representation of the nature of the bainite reaction in heterogeneous 300M steel. © 1990 The Metallurgical of Society of AIME.