Title: Effect of the random spatial distribution of nuclei on the transformation plasticity in diffusively transforming steel

Authors: Romain Quey, Fabrice Barbe, Ha Hoang, Lakhdar Taleb

Addresses: Ecole des Mines de Saint Etienne, Laboratoire PECM, CNRS UMR 5146, 42023 Saint Etienne, France. ' INSA Rouen, Groupe de Physique des Materiaux, CNRS UMR 6634, 76801 Saint Etienne du Rouvray, France; Institute for Materials Research, Avenue de l'Universite, 76801 Saint Etienne du Rouvray, France. ' INSA Rouen, Groupe de Physique des Materiaux, CNRS UMR 6634, 76801 Saint Etienne du Rouvray, France; Institute for Materials Research, Avenue de l'Universite, 76801 Saint Etienne du Rouvray, France. ' INSA Rouen, Groupe de Physique des Materiaux, CNRS UMR 6634, 76801 Saint Etienne du Rouvray, France; Institute for Materials Research, Avenue de l'Universite, 76801 Saint Etienne du Rouvray, France

Abstract: The γ → α diffusive phase transformations of steels can lead to transformation plasticity (TRIP) if accompanied of an external loading stress or a pre-hardening of the parent phase. The most current approaches of its modelling are based on the Greenwood-Johnson mechanism; they call upon hypotheses (about microstructure morphology, constitutive laws...) which are at the origin of discrepancies between predictions and experimental observations in particular loading cases. Some of these restricting hypotheses can be eliminated with a micromechanical finite elements approach, where the elastoplastic interactions between phases are determined at the micro-scale of a volume element containing hundreds of growing particles (Barbe et al., 2005, 2008). This paper deals with the effect of the spatial distribution of product phase nuclei on the global kinetics and transformation-induced plasticity (TRIP) in the volume element. Two distributions are considered: uniform random and at preferential nucleation sites of a Voronoi tesselation mimicking austenite microstructure.

Keywords: transformation plasticity; Voronoi tessellation; steel diffusive transformation; nuclei random distribution; micromechanical modelling; finite element method; FEM; phase transformation; elastoplastic interactions; kinetics; austenite microstructure.

DOI: 10.1504/IJMMP.2010.037612

International Journal of Microstructure and Materials Properties, 2010 Vol.5 No.4/5, pp.354 - 364

Published online: 20 Dec 2010 *

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