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Baptiste Flipon

Publications and source records attributed to Baptiste Flipon.

6 recordsLinked to original sources

InfinityEBSD : Metrics-Guided Infinite-Size EBSD Map Generation With Diffusion Models

Materials performance is deeply linked to their microstructures, which govern key properties such as strength, durability, and fatigue resistance. EBSD is a major technique for characterizing these microstructures, but acquiring large and statistically representative EBSD maps remains slow, costly, and often limited to small regions. In this work, we introduce InfinityEBSD, a diffusion-based method for generating monophase realistic EBSD maps of arbitrary size, conditioned on physically meaningful microstructural metrics. This approach supports two primary use cases: extending small experimental EBSD maps to arbitrary sizes, and generating entirely new maps directly from statistical descriptors, without any input map. Conditioning is achieved through eight microstructural descriptors, including grain size, grain perimeter, grain inertia ratio, coordination number and disorientation angle distribution, allowing the model to generate maps that are both visually realistic and physically interpretable. A patch-wise geometric extension strategy ensures spatial continuity across grains, enabling the model to produce large-scale EBSD maps while maintaining coherent grain boundaries and orientation transitions. The generated maps can also be exported as valid Channel Text Files (CTF) for immediate post-processing and analysis in software such as MTEX or simulation environments like DIGIMU. We quantitatively validate our results by comparing distributions of the guiding metrics before and after generation, showing that the model respects the statistical targets while introducing morphological diversity. InfinityEBSD demonstrates that diffusion models, guided by physical metrics, can bridge the gap between synthetic and realistic materials representation, paving the way for future developments such as 3D realistic microstructure generation from 2D data.

cond-mat.mtrl-sci

Comparison of grain growth mean-field models regarding predicted grain size distributions

Mean-field models have the ability to predict grain size distribution evolution occurring through thermomechanical solicitations. This article focuses on a comparison of mean-field models under grain growth conditions. Different microstructure representations are considered and discussed, especially regarding the consideration of topology in the neighborhood construction. Experimental data obtained with a heat treatment campaign on a 316L austenitic stainless steel are used for material parameters identification and as a reference for model comparisons. Mean-field models are also confronted to both mono- and bimodal initial grain size distributions to investigate the interest of introducing neighborhood topology in microstructure predictions models. This article exposes that improvements in the predictions are obtained in monomodal cases for topological models. In bimodal test, no comparison with experimental data were performed as no data were available. But relative comparisons between models indicate few differences in predictions. The interest of neighborhood topology in grain growth mean-field models gives overall small improvements compared to classical mean-field models when comparing implementation complexity.

cond-mat.mtrl-sci

Modeling CDRX and PDRX during hot forming of zircaloy-4

A recently developed full field level-set model of continuous dynamic recrystallization is applied to simulate zircaloy-4 recrystallization during hot compression and subsequent heat treatment. The influence of strain rate, final strain and initial microstructure is investigated, by experimental and simulation tools. The recrystallization heterogeneity is quantified. This enables to confirm that quenched microstructures display a higher extent of heterogeneity. The simulation results replicate satisfactorily experimental observations. The simulation framework is especially able to capture such recrystallization heterogeneity induced by a different initial microstructure. Finally, the role of intragranular dislocation density heterogeneities over the preferential growth of recrystallized grains is pointed out thanks to additional simulations with different numerical formulations.

cond-mat.mtrl-sci

Simulation of continuous dynamic recrystallization using a level-set method

Dynamic recrystallization is one of the main phenomena responsible for microstructure evolutions during hot forming. Consequently, getting a better understanding of DRX mechanisms and being able to predict them is crucial. This paper proposes a full-field numerical framework to predict the evolution of subgrain structures upon grain growth, continuous dynamic and post-dynamic recrystallization. The microstructure representation into the numerical environment is presented. The developments made to improve substructure description are detailed extensively. Using these simulation tools, simulation of grain growth of a fully substructured microstructure are run. The influence of microstructure topology, of subgrain parameters and of some remaining stored energy due to plastic deformation is discussed. An analysis of the criterion for discrimination of recrystallized grains is proposed. Finally, the ability of the framework to model continuous dynamic and post-dynamic recrystallization is assessed upon a case study. The influence of grain boundary properties and of nucleation rules are studied. The representativity of the results in regards of experimental data will be discussed in an upcoming article.

cs.CE

Characterization and modeling of the influence of initial microstructure on recrystallization of zircaloy-4 during hot forming

The present article proposes a detailed study of recrystallization of zircaloy-4 under hot forming conditions by means of experimental and numerical tools. Thermomechanical tests and characterization campaigns that have been necessary for this work are described. Then, the different microstructure evolution mechanisms are characterized, from the simplest one to the most complex. Grain growth kinetics is quantified and the influence of second phase particle population is analyzed. Then, a complete study of dynamic and post-dynamic recrystallization is provided. The occurrence of a continuous mechanism is confirmed and the influence of thermomechanical conditions upon recrystallization is assessed. Later, the numerical framework used to simulate grain growth, continuous and post-dynamic recrystallization is presented. After having successfully reproduced the grain coarsening kinetics with and without second phase particles, the model is used to describe continuous dynamic recrystallization and post-dynamic recrystallization from an initial equiaxed and fully recrystallized microstructure. The agreement between experimental and numerical results is assessed in detail. Finally, post-dynamic recrystallization is simulated, starting from two deformed microstructures characterized by electron back-scattered diffraction technique and immersed into simulations. This allows to discuss and reproduce the influence of initial microstructure.

cond-mat.mtrl-sci

Level-Set modeling of grain growth in 316L stainless steel under different assumptions regarding grain boundary properties

Two finite element level-set (FE-LS) formulations are compared for the modeling of grain growth of 316L stainless steel in terms of grain size, mean values and histograms. Two kinds of microstructures are considered, some are generated statistically from EBSD maps and the others are generated by immersion of EBSD data in the FE formulation. Grain boundary (GB) mobility is heterogeneously defined as a function of the GB disorientation. On the other hand, GB energy is considered as heterogeneous or anisotropic, respectively defined as a function of the disorientation and both the GB misorientation and the GB inclination. In terms of mean grain size value and grain size distribution (GSD), both formulations provide similar responses. However, the anisotropic formulation better respects the experimental disorientation distribution function (DDF) and predicts more realistic grain morphologies. It was also found that the heterogeneous GB mobility described with a sigmoidal function only affects the DDF and the morphology of grains. Thus, a slower evolution of twin boundaries (TBs) is perceived.

cond-mat.mtrl-sci