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The influence of cooling rate from the intercritical αγ region on the microstructure of a vanadium bearing HSLA steel was investigated by transmission electron microscopy. Oil quenching produced an essentially ferrite-martensite dual phase structure with ∼4 vol pct of fine particle and thin film retained austenite. In contrast, the slower air cooling resulted in a larger amount (∼10 vol pct) of retained austenite in addition to the ferrite and martensite phases. A major portion of the retained austenite in the air cooled specimen was of the blocky morphology (1 to 6 μm , with the remainder eing the submicron variety, similar to that of the oil quenched specimen. In conformance with the terminology of earlier studies, “retained” ferrite and “transformed” ferrite were observed in the air cooled steel while oil quenching completely suppressed the transformed ferrite. Retained ferrite, the cleaner of the two in terms of …