Study of Nucleation Mechanisms during Dynamic Recrystallization of a Coarse Nb Microalloyed Austenite

Abstract:

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.

• Periodical: Materials Science Forum (Volumes 467-470)
• Pages: 1169-1174
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.467-470.1169
• Online since: October 2004
• Authors: Ana Isabel Fernández-Calvo, Beatriz López, J.M. Rodriguez-Ibabe
• Keywords: Dynamic Recrystallization (DRX), Nb Microalloyed Steel, Thin Slab Casting

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