Study on Ferrite Intragranular Nucleation in a V-Microalloyed Steel
The intragranular nucleation of ferrite has been studied in a V-microalloyed steel (C=0.102; Mn=1.479; V=0.140; N=0.016, %wt). By means of hot torsion tests, recrystallizationprecipitation-time-temperature (RPTT) diagrams have been drawn which show the precipitation kinetics and the recrystallization-precipitation interaction at any temperature. RPTT diagrams were determined at two strains, 0.20 and 0.35 respectively. Deformation tests were carried out at 890°C and different holding times, corresponding to moments before the start of precipitation, during precipitation and after precipitation had ended, respectively. In order to relate the precipitation state with the intragranular nucleation, the strengthening of austenite was measured taking into account the non-recrystallized austenite fraction prior to the phase transformation. In this way, the possibility of V-nitrides acting as nucleation sites was evaluated by comparison of ferrite grain size versus holding time. Thus it was found that the precipitate size and precipitated volume are influencing the intragranular nucleation, although this is not a strong influence.
J.M. Rodriguez-Ibabe, I. Gutiérrez, B. López and A. Iza-Mendia
S.F. Medina et al., "Study on Ferrite Intragranular Nucleation in a V-Microalloyed Steel", Materials Science Forum, Vols. 500-501, pp. 371-378, 2005