Solid-state nucleation of acicular ferrite on minerals added to molten steel

J. M. Gregg and H. K. D. H. Bhadeshia


A technique has been developed for making samples of steel with controlled additions of powdered mineral phases. Alloys made using this technique have been studied from the point of view of the acicular ferrite microstructure, which forms when ferrite plates nucleate heterogeneously on non-metallic inclusion. It is observed that titanium oxide particles are most efficient in nucleating acicular ferrite. It is suspected that nucleation is enhanced around these particles because of their chemical interaction with the surrounding steel, causing localised depletion in either carbon or manganese. Such local depletion zones thermodynamically stabilize the ferrite phase over the parent austenite, thus causing nucleation.

Acta Materialia, 45 (1997) 739-748.

Envelope Coefficients Filling welds Hot Delta
Satoh Fields Piping European welds Poles
Mixed Creep Extraordinary ductility Problems Mechanical stabilisation

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