World's first commercial CMOS Electron Backscatter Diffraction Detector: applications for a few ceramic materials

International audienc

Characterization and modeling of oxides precipitation in ferritic steels during fast non-isothermal consolidation

International audienceno abstrac

Microstructure, texture and mechanical properties with raw surface states of Ti-6Al-4V parts built by L-PBF

International audienceDue to dramatic thermal gradients and cooling rates induced by Laser Powder Bed Fusion (L-PBF), Ti-6Al-4V as-built parts show a fine martensitic microstructure with high residual stresses that are detrimental for their mechanical behaviour. In order to optimize the properties and meet the product requirements, post-processing heat treatments are often compulsory. The present work first describes the microstructure (residual stresses, beta grains and laths size, crystallographic texture) and the mechanical behaviour (impact and tensile tests) of as-built parts with raw surface. Then, one discusses the effect of a stress-relieve sub-transus heat treatment on the strength/ductility compromise

Fast high-temperature consolidation a novel way to understand the microstructural heterogeneities in nano-reinforced ferritic steels

International audienceOxide-Dispersion Strengthened (ODS) ferritic steels were produced by powder metallurgy using a field-assisted sintering technique called spark plasma sintering (SPS). A multiscale characterization using electron microscopy combined with an in situ synchrotron X-Ray Diffraction allowed to understand the evolution of the heterogeneous microstructure. The influence of oxides precipitation was quantified by nanoscale observations to explain the microstructure heterogeneities in ferritic ODS alloys

Development of an austenitic/martensitic gradient steel by additive manufacturing

International audienceIn many applications, additive manufacturing techniques are rising to build, layerby-layer,component with complex shapes and specific microstructures. DirectMetal Deposit (DMD) process allows to tune the material's composition usingdifferent powder feeder. In this study, we focused on a gradient from a 316Laustenitic stainless steel to a 9Cr-1Mo martensitic steel. These steels are widelyused for nuclear applications, but due to their chemical composition differences,welding them is uneasy. In this study, microstructures obtained by Tungsten InertGas welding are compared with graded parts obtained by powder metallurgy, afterSpark Plasma Sintering or additive manufacturing with Direct Metal Depositprocess

Tailoring the microstructure and the mechanical properties of ultrafine grained high strength ferritic steels by powder metallurgy

International audienceno abstrac

Direct-ink writing and compression behavior by in situ micro-tomography of architectured 316L scaffolds with a two-scale porosity

International audienc

Non-symmetrical fatigue life of nodular graphite cast iron under non-proportional multi-axial cyclic loading

cited By 0Non-proportional axial-torsional loading fatigue tests on nodular cast iron revealed a non-symmetrical behavior of the fatigue life relatively to the phase shift angle δ = 90° between axial and torsion loads. This behavior was in agreement with fatigue crack orientation investigated using optical and electron microscopy. Elasto-plastic finite element model (FEM) were used to assess the crack orientation behavior and it could explain this non-symmetrical behavior by the non-symmetrical values of both σ I and σ I / σ II ratio relatively to δ = 90°. FEM revealed that for the δ < 90° loads, principal stress was applied essentially at critical planes of low angle ϕ n , thus occurrence of tensile cracks mode was higher for δ < 90° than for δ > 90° load, which reduces the fatigue life. σ I / σ II ratio strongly influenced the dominant crack mode. When the applied loads were torsion σ I /σ II = 1, cracks were observed to occur, equally, in modes I and II. Presence of the non-propagating failure (mode II) significantly increased the fatigue life. Conversely, for high phase shift, where σ I / σ II ≫ 1, crack mode I dominated and crack driving force remained high during the whole fatigue cycle, inducing a lower fatigue limit. © 201

Assessment of consolidation of oxide dispersion strengthened ferritic steels by spark plasma sintering: from laboratory scale to industrial products

International audienc

Direct-ink writing of strong and biocompatible titanium scaffolds with bimodal interconnected porosity

International audienceAdditive manufacturing of porous Ti6Al4V (Ti64) parts is promising for biomedical applications. In this study, Ti64 scaffolds with two scales of interconnected porosity networks were developed using a direct-ink writing process. Inks were made by dissolving a copolymer (Pluronic F-127) in water to obtain a hydrogel, which was then loaded with Ti64 particles. Both Pluronic F-127 amount in the hydrogel and solid loading influenced ink printability, as shown by rheological measurements and printing accuracy investigation. The best compromise was obtained for a 25 wt% Pluronic hydrogel loaded with 50 vol% of Ti64 particles. A partial sintering of 2 h at 1200 ∘ C led to interconnected micropores within strut, which was characterised by X-Ray computed tomography. Sintered scaffolds presented a compressive strength higher than bone, with a similar Young's modulus. According to their biocompatibility, final microstructure and mechanical properties, these scaffolds show a promising potential for load-bearing implants