Investigation of massive ferrite in an interstitial-free steel

The formation of massive ferrite in an interstitial-free (IF) steel with three different austenitization conditions (at 1200, 1100 and 1000 °C respectively for 3 min) has been investigated. To conduct the rapid continuous-cooling transformations at a cooling rate of 500 °C/s, hollow rod specimens were employed in a dilatometer. Thermal arrests, which were associated with the phase transition, were detected in the cooling curves, and thereby the massive ferrite transformation temperatures were determined. The corresponding treated samples were studied by optical metallography and transmission electron microscopy. The features of massive ferrite and its transformation characterization are discussed.