Study of Nucleation Mechanisms during Dynamic Recrystallization of a Coarse Nb Microalloyed Austenite
The dynamic recrystallization (DRX) behavior of a coarse grain sized Nb microalloyed austenite (∼ 800 µm), typical of thin slab casting processes, has been studied. Continuous torsion tests were carried out at different, Z, Zener-Hollomon parameter values. It has been observed that as Z increases the curves move to higher values of stress and both the peak, εp, and steady state, εss, occur at larger strains, with an increase in the εss - εp strain difference. Consequently, an increment in Z produces a delay in the beginning and the progression of the DRX process. In the present work, it has been found that the pre-existing grain boundaries are the most favorable nucleation sites for DRX for all Z values, the nucleation mechanisms being related to strain induced migration of high angle grain boundaries. However, in the case of high Z values, intragranular nucleation on defects generated during deformation is also observed. The microstructure analysis denotes also that dynamic recrystallization is a process dominated by repeated nucleation with limited growth.
B. Bacroix, J.H. Driver, R. Le Gall, Cl. Maurice, R. Penelle, H. Réglé and L. Tabourot
A. I. Fernández-Calvo et al., "Study of Nucleation Mechanisms during Dynamic Recrystallization of a Coarse Nb Microalloyed Austenite", Materials Science Forum, Vols. 467-470, pp. 1169-1174, 2004