References of "Lecomte-Beckers, Jacqueline"
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See detailProcessing metallic materials by additive technologies - Specificities of the thermal history and microstructures
Mertens, Anne ULg; Lecomte-Beckers, Jacqueline ULg

Conference given outside the academic context (2014)

Additives technologies currently attract a growing interest as they are particularly versatile and well adapted for the production of small series e.g. of metallic parts. Beyond the great diversity of the ... [more ▼]

Additives technologies currently attract a growing interest as they are particularly versatile and well adapted for the production of small series e.g. of metallic parts. Beyond the great diversity of the concerned processes (laser beam melting, electron beam melting, laser cladding…) and metallic alloys, some common features may be highlighted: (1) the strong directionality of additive processes, due to the fact that parts are fabricated “layer-by-layer”; (2) the ultra-fast heating and cooling cycles, following the displacement of the beam(s) away from the working zone. The present paper aims at illustrating these two major features of additive techniques through case studies involving the most common metallic alloys (steels, Al- or Ti-based alloys…), thus highlighting the opportunities pertaining to additive technologies for the optimisation of materials microstructures and of the resulting properties. [less ▲]

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See detailLes composites à matrice métallique/céramique – De nouveaux procédés de fabrication pour de nouvelles applications
Mertens, Anne ULg; Lecomte-Beckers, Jacqueline ULg

Conference (2014, May 20)

A l’heure où la plupart des matériaux composites essentiellement structuraux sont faits d’une matrice à base polymère, les matériaux composites à matrice métallique ou céramique offrent de nouvelles ... [more ▼]

A l’heure où la plupart des matériaux composites essentiellement structuraux sont faits d’une matrice à base polymère, les matériaux composites à matrice métallique ou céramique offrent de nouvelles perspectives en termes de performances et de durabilité. Le présent exposé s’attache plus particulièrement à retracer les possibilités offertes par de nouvelles méthodes de mise en oeuvre telles que la friction-malaxage et les techniques d’impression 3D, aussi bien en termes d’amélioration des propriétés mécaniques des matériaux composites que des fonctionnalités inédites qui peuvent leur être conférées. [less ▲]

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See detailComparison of the wear behavior of high speed steel grades obtained from conventional casting and laser cladding
Hashemi, Seyedeh Neda ULg; Dedry, Olivier ULg; Lecomte-Beckers, Jacqueline ULg et al

in Materiaux et tribologie jift 2014 (2014, May)

The wear characteristics of three high speed steel grades were studied, one of them being obtained from a conventional casting process and two others originated from a laser cladding route. Tribological ... [more ▼]

The wear characteristics of three high speed steel grades were studied, one of them being obtained from a conventional casting process and two others originated from a laser cladding route. Tribological tests were carried out at room temperature using a “pin-on-disc” device. The setting of the wear test parameters together with the microstructure of the studied materials seems to strongly influence the subsequent abrasion and wear mechanisms. The results show that the laser cladded high speed steel materials resist better to wear thanks to their ultrafine microstructure compared to the conventional cast material. [less ▲]

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See detailProcessing of alloy Ti-6Al-4V and of stainless steel 316L by Laser Beam Melting
Mertens, Anne ULg; Paydas, Hakan ULg; Reginster, Sylvie ULg et al

Conference (2014, May)

Additive manufacturing processes such as Selective Laser Melting (SLM) appear very promising in view of the economic production of near-net-shape, complex and (almost) fully dense parts from metallic ... [more ▼]

Additive manufacturing processes such as Selective Laser Melting (SLM) appear very promising in view of the economic production of near-net-shape, complex and (almost) fully dense parts from metallic materials such as Ti alloys and stainless steels. Practically, in SLM, a metallic powder is deposited layer-by-layer in a powder bed and then molten locally according to the desired shape. An important feature of this process is that the structure undergoes an ultra-fast cooling once the beam leaves the working zone, thus giving rise to strongly out-of-equilibrium microstructures. In the case of Ti alloy Ti-6Al-4V, in particular, the microstructural anisotropy resulting from the epitaxial growth of the newly deposited layer on the material previously solidified has been shown to exert a very strong influence on the mechanical properties [1] In the present work, the thermophysical behaviour of Ti-alloy Ti-6Al-4V and of stainless steel 316L has been characterised in details, in order to reach a better understanding of the phenomena controlling the microstructures and mechanical properties of parts. In particular, the thermal conductivity of Ti-alloy Ti-6Al-4V and of stainless steel 316L at high temperature has been determined by combining dilatometry, Differential Scanning Calorimetry (DSC) and laser flash diffusivimetry based on Laplace’s equation. Since Ti-alloy Ti-6Al-4V and stainless steel 316L exhibit quite different physical behaviours, their careful comparison is shown to shed more light into the role of phenomena such as epitaxial growth, out-of-equilibrium phase transformations and/or internal stresses in the additive manufacturing of metallic materials. [less ▲]

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See detailTechniques additives vs techniques conventionnelles-les microstructures
Mertens, Anne ULg; Lecomte-Beckers, Jacqueline ULg

Conference given outside the academic context (2014)

Très flexibles et particulièrement bien adaptées à la production de petites séries, les techniques additives suscitent un intérêt croissant, notamment pour la mise en oeuvre de matériaux métalliques. Par ... [more ▼]

Très flexibles et particulièrement bien adaptées à la production de petites séries, les techniques additives suscitent un intérêt croissant, notamment pour la mise en oeuvre de matériaux métalliques. Par-delà la diversité des techniques que ce terme recouvre (laser beam melting, electron beam melting, laser cladding…) et par-delà la variété des alliages qu’elles permettent de mettre en oeuvre, quelques caractéristiques récurrentes se dessinent: 1) La nature fortement directionnelle des procédés additifs, lié au fait que la pièce est fabriquée “couche par couche” 2) Des cycles de chauffe et de refroidissement ultra-rapides, en fonction des déplacements du/des faisceau(x) La présente communication s’attache à illustrer ces deux caractéristiques essentielles des techniques additives au moyen d’exemples touchant aux principaux alliages métalliques (aciers, alliages d’aluminium ou de titane…), et à en dégager les risques et les opportunités qu’offrent les techniques additives du point vue du contrôle et de l’optimisation des microstructures et des propriétés d’usage qui en découlent… [less ▲]

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See detailMicrostructures and Mechanical Properties of Stainless Steel AISI 316L Processed by Selective Laser Melting
Mertens, Anne ULg; Reginster, Sylvie ULg; Contrepois, Quentin et al

in Materials Science Forum (2014), 783-786 (2014)

In this study, samples of stainless steel AISI 316L have been processed by selective laser melting, a layer-by-layer near-net-shape process allowing for an economic production of complex parts. The ... [more ▼]

In this study, samples of stainless steel AISI 316L have been processed by selective laser melting, a layer-by-layer near-net-shape process allowing for an economic production of complex parts. The resulting microstructures have been characterised in details in order to reach a better understanding of the solidification and consolidation processes. The influence of the processing parameters on the mechanical properties was investigated by means of uniaxial tensile testing performed on samples produced with different main orientations with respect to the building direction. A strong anisotropy of the mechanical behaviour was thus interpreted in relation with the microstructures and the processing conditions. [less ▲]

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See detailRapport Final, Projet FEDER Programmation 2007-2013, portefeuille de projets SINUS : Simulation Numérique Haute Performance
Lecomte-Beckers, Jacqueline ULg; Mertens, Anne ULg; Carton, Marc et al

Report (2014)

Le portefeuille de projets SINUS : Simulation Numérique Haute Performance, s'inscrit dans le cadre des mesures 2.2 de valorisation du potentiel des centres de recherche en Wallonie. Trois projets ... [more ▼]

Le portefeuille de projets SINUS : Simulation Numérique Haute Performance, s'inscrit dans le cadre des mesures 2.2 de valorisation du potentiel des centres de recherche en Wallonie. Trois projets composent le portefeuille SINUS: une action 2.2.1 Équipements technologiques exceptionnels, une action 2.2.2 Projets de recherche transversaux en partenariat, une action 2.2.4 Optimisation de l'offre de services technologiques des centres de recherches agréés.Ce rapport s'inscrit dans l'action 2.2.2 des projets de recherche transversaux en partenariat. Cette action vise à développer des méthodes numériques de nouvelle génération en collaboration avec des centres de recherche universitaires et agréés et des entreprises répondant aux besoins de l’industrie. Les domaines couverts sont la modélisation des processus de fabrication, des matériaux et des structures, la mécanique des fluides et l’optimisation multidisciplinaire. Au sein de cette action, différents lots ont été définis : Lot 1 Modélisation avancée d'écoulements complexes multi-physiques, Lot 2 Modélisation avancée multi-échelles des matériaux et des structures, Lot 3 Modélisation avancée des procédés de fabrication, Lot 4 Optimisation multidisciplinaire. [less ▲]

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See detailStudy of residual stresses in bimetallic work rolls
Neira Torres, Ingrid ULg; Gilles, Gaëtan ULg; Tchuindjang, Jérôme Tchoufack ULg et al

in Advanced Materials Research (2014), 996

An experimental campaign of compression tests, differential thermal analysis (DTA), differential scanning calorimetry ( DSC), dilatometry and microstructure analysis has been performed, as well as the ... [more ▼]

An experimental campaign of compression tests, differential thermal analysis (DTA), differential scanning calorimetry ( DSC), dilatometry and microstructure analysis has been performed, as well as the identification of the material data set for finite element ( FE) analysis of bimetallic rolls. This article numerically investigates the stress and strain fields after the cooling stage and it checks their effect on the subsequent heat treatment step. As bimetallic rolls have a different material for core and shell, the effect of the roll size and the shell thickness on residual stresses is also studied. [less ▲]

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See detailElaboration of Thin Foils in Copper and Zinc by Self-Induced Ion Plating
Giraud, Eliane; Pace, Sergio ULg; Lecomte-Beckers, Jacqueline ULg

in Materials Science (2014), 20(2), 160-164

The aim of this work was to determine the ability to produce thin metallic foils by self-induced ion plating. Foils of pure copper and pure zinc with a thickness of 35 μm have been successfully produced ... [more ▼]

The aim of this work was to determine the ability to produce thin metallic foils by self-induced ion plating. Foils of pure copper and pure zinc with a thickness of 35 μm have been successfully produced and their characteristics have been compared to foils obtained by conventional techniques (i. e. electroplating and rolling). Results show the following: (i) more or less compact microstructures can be obtained by self-induced ion plating depending on gas pressure and substrate temperature; (ii) microstructures obtained by self-induced ion plating are quite different from those obtained by electroplating and rolling; (iii) Young’s modulus depends on foils roughness; (iv) hardness depends on grain size by exhibiting a Hall-Petch behavior in the case of copper foils and an “inverse” Hall-Petch behavior in the case of zinc foils. [less ▲]

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See detailMechanical properties of alloy Ti-6Al-4V and of stainless steel 316L processed by Selective Laser Melting: Influence of out-of-equilibrium microstructures
Mertens, Anne ULg; Reginster, Sylvie ULg; Paydas, Hakan ULg et al

in Powder Metallurgy (2014), 57(3), 184-189

Ti-6Al-4V and stainless steel 316L have been processed by selective laser melting under similar conditions, and their microstructures and mechanical behaviours have been compared in details. Under the ... [more ▼]

Ti-6Al-4V and stainless steel 316L have been processed by selective laser melting under similar conditions, and their microstructures and mechanical behaviours have been compared in details. Under the investigated conditions, Ti-6Al-4V exhibits a more complex behaviour than stainless steel 316L with respect to the occurrence of microstructural and mechanical anisotropy. Moreover, Ti-6Al-4V appears more sensitive to the build-up of internal stresses when compared with stainless steel 316L, whereas stainless steel 316L appears more prone to the formation of “lack of melting” defects. This correlates nicely with the difference in thermal conductivity between the two materials. Thermal conductivity was shown to increase strongly with increasing temperature and the thermophysical properties appeared to be influenced by variations in the initial metallurgical state. [less ▲]

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See detailFriction Stir Processing of Magnesium Matrix Composites Reinforced with Carbon Fibres or Carbon Nanotubes - A Comparative Study
Mertens, Anne ULg; Simar, Aude; Garray, Didier et al

Conference (2013, December 05)

The poor wettability of carbon substrates by liquid Mg and, in the case of carbon nanotubes (CNTs), their strong tendency to agglomerate, are major obstacles to the large-scale production of C-Mg ... [more ▼]

The poor wettability of carbon substrates by liquid Mg and, in the case of carbon nanotubes (CNTs), their strong tendency to agglomerate, are major obstacles to the large-scale production of C-Mg composites by classical ‘liquid-state’ processing routes such as squeeze casting. As an innovative ‘solid state’ process, Friction Stir Processing (FSP) hence appeared as a very promising alternative for the production of C-Mg composites, although the method for inserting the reinforcing phase - in grooves or holes machined in the matrix material - remained time-consuming and labour-intensive. More recently, the present authors proposed a new and easier technique for the insertion of C fibres in FSPed Mg-matrix composites i.e. FSP of a C fabric stacked between two metal sheets. In the current work, the feasibility of extending this latter method to the production of CNTs-Mg composites has been assessed. “Bucky papers” – thin disks made from agglomerated CNTs, thus ensuring for their safe handling – were stacked between two sheets of Mg alloy AZ31B, and the resulting sandwich was FSPed. The effect of FSP experimental parameters such as the rotational and advancing speeds or the number of passes on the microstructural changes occuring upon processing has been studied and compared with the case of C fibres-Mg composites. Moreover, a particular attention has been given to the distribution of the reinforcements in the Mg matrix and to the characterization of the resulting mechanical properties. [less ▲]

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