Effect of the random spatial distribution of nuclei on the transformation plasticity in diffusively transforming steel
Résumé
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.
Mots clés
micromechanical finite-elements modeling
transformation-induced plasticity
TRIP
steel diffusive transformation
nuclei random distribution
transformation plasticity
Voronoi tessellation
micromechanical modelling
finite element method
phase transformation
elastoplastic interactions
austenite microstructure
Domaines
Matériaux
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