Effect of Carbon Content on the Potency of the Intragranular Ferrite Formation

The effect of the carbon content on the potency of the intragranular ferrite (IGF) formation for each inclusion size is investigated in the present work. The TiN inclusion was detected to be the effective nucleation site for the IGF formation in the Fe–0.2 mass% C alloy and the Fe–0.4 mass% C alloy. It is noted that the potency of the IGF formation for each inclusion size is decreased with the increase of carbon content. Moreover, the critical diameters of the TiN, TiO, and VN inclusions in the steels with different carbon contents are calculated based on the classical nucleation theory. The calculated critical diameter is also found to be decreased with the increase of carbon content. This is in agreement with the experiment results. Finally, the decrease of the potency of IGF formation for each inclusion size is due to a larger amount of pearlite formation in the steel containing a higher carbon content, which is detected by differential scanning calorimetry (DSC) measurements.