Ferrite formation in heterogeneous dual-phase steels

H.K.D.H. Bhadeshia

Abstract

We examine the formation of ferrite within dual-phase steels that exhibit compositional banding, specifically focusing on the manganese distribution in Fe-Mn-C alloys. This research investigates how chemical heterogeneity influences the maximum volume fraction of ferrite achievable compared to uniform, homogeneous metals. By utilizing isothermal sections and paraequilibrium phase boundaries, it is demonstrated that the standard lever rule fails to accurately predict phase behavior in these non-uniform systems. The analysis concludes that the final microstructure and resulting carbon content of the remaining austenite depend heavily on the specific concentration gradients encountered during the transformation process. Ultimately, the study provides a theoretical framework for understanding why banded steels deviate from the expected metallurgical properties of their homogeneous counterparts.

Scripta Metallurgica 17 (1983) 857-860.

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