References of "Lecomte-Beckers, Jacqueline"
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See detailImprovement in Thixoforging of 7075 Aluminium Alloys at High Solid Fraction
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg et al

in Solid State Phenomena (2008), 141-143

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<1). 7075 aluminium alloys have been used as a feedstock for thixoforging in order to investigate thixoformability of a ... [more ▼]

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<1). 7075 aluminium alloys have been used as a feedstock for thixoforging in order to investigate thixoformability of a high performance aluminium alloy at high solid fraction. Higher solid fraction of 7075 alloy is less sensitive to temperature, avoids metal splash at high speed and allows laminar flow at high speed. Hot tool combined with lubricant tool coating are used to slow down the solidification rate of the high solid fraction metal by decreasing thermal exchanges with the tool. Improved thermal and forming parameters [1-2] will be applied to produce an automotive component by thixoforging and mechanical properties have been measured from tensile samples. High mechanical properties are obtained after T6 thermal treatment. [less ▲]

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See detailAlloy Characterization to Adapt Steels to Thixoforming: Study of a High Chromium High Carbon Steel
Fraipont, Céline; Lecomte-Beckers, Jacqueline ULg

in Solid State Phenomena (2008), 141-143

This paper deals with the examination of the influence of alloying elements on the thixoformability of a Cr steel. It focuses on the liquid fraction curves of different Cr steels with modifications of ... [more ▼]

This paper deals with the examination of the influence of alloying elements on the thixoformability of a Cr steel. It focuses on the liquid fraction curves of different Cr steels with modifications of composition. The effect of composition modifications was observed. The solid fraction versus temperature has been obtained by a thermodynamics software (MTData) and by Differential Scanning Calorimetry (DSC), limited to low heating rates. MTData permits to obtain information on the influence of alloying elements, with the advantage of the possibility to change the chemical composition very easily. The DSC tests determine the influence of the heating rate on these curves. [less ▲]

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See detailInfluence of Alloying Elements on the Thixoformability of a Chromium Steel
Fraipont, Céline; Lecomte-Beckers, Jacqueline ULg

in International Journal of Material Forming (2008), 1(1), 997-1000

This paper deals with the examination of the influence of alloying elements on the thixoformability of a chromium steel. It focuses on the liquid fraction curves of various chromium steels with and ... [more ▼]

This paper deals with the examination of the influence of alloying elements on the thixoformability of a chromium steel. It focuses on the liquid fraction curves of various chromium steels with and without modification of composition. The liquid fraction versus temperature has been obtained by MTData, a thermodynamic prediction package, and by Differential Thermal Analysis (DTA), limited to low heating rates. The correlation between liquid fraction and temperature has been studied. The effect of modifications of composition and of heating rate was observed. First, the thermodynamical calculations allow the study of the influence of alloying elements with variations in chemical composition. Secondly, the DTA tests offer the possibility to observe the influence of heating rate on liquid fraction curve parameters. All these results lead to the identification of the initial parameters necessary to perform inductive heating and quenching tests, and so to approach the industrial process. [less ▲]

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See detailExtrusion tests of 7075 aluminium alloy at high solid fraction
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg et al

in International Journal of Material Forming (2008), 1(1), 1019-1022

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<fs<1). 7075 aluminium alloy has been used as a feedstock for thixoforging in order to investigate thixoformability of a ... [more ▼]

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<fs<1). 7075 aluminium alloy has been used as a feedstock for thixoforging in order to investigate thixoformability of a high performance aluminium alloy at high solid fraction. Higher solid fraction of 7075 alloy is less sensitive to a drop in temperature, avoids metal splash at high speed, allows laminar flow at high speed. Hot tool is used to slow down the solidification rate of the high solid fraction metal by decreasing thermal exchanges. To determine the best parameters to achieve maximum mechanical properties in thixoforging of 7075 aluminum alloy, we need to consider the impact of some parameters such as tool temperature, shear rate. For this, we use extrusion tests with constant speed [1] where these parameters are known. The result of this study is that each parameter has its level of impact on the thixoforging: the temperature of the tool and the deformation rate shouldn't be high to avoid cracks. Thermal exchanges between the material flow and the tool have to be reduced to avoid high solidification rate [2]. [less ▲]

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See detailSteel thixoforming, influence of forming parameters on the microstructure
Pierret, Jean-Christophe ULg; Rassili, Ahmed ULg; Vaneetveld, Grégory ULg et al

in International Journal of Material Forming (2008), 1(1), 1011-1014

Forming of parts in the semi-solid state is quite a complex process, especially for high melting point alloys such as steel. A reason for this complexity is the amount of parameters involved in the ... [more ▼]

Forming of parts in the semi-solid state is quite a complex process, especially for high melting point alloys such as steel. A reason for this complexity is the amount of parameters involved in the process. Among these we could quote liquid fraction, shear rate, shape factor, contiguity, tool temperature, agglomeration level, heating rate, protecting gas, temperature distribution, lubricant. Of course all of these parameters don’t have the same order of importance. In this paper we show the influence of a set of chosen parameters and we highlight their effects on the microstructure and so, on the deformation behavior. The studied parameters are the heating conditions, the tool temperature, the part temperature, the thermal exchanges between the part and the dies and the forming rate. [less ▲]

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See detailOptimization of the formulation and post-treatment of stainless steel for rapid manufacturing
Vaneetveld, Grégory ULg; Clarinval, A. M.; Dormal, T. et al

in Journal of Materials Processing Technology (2008), 196(1-3), 160-164

Rapid prototyping process called Optoform shapes functional parts from a photocurable paste. This paste contains metal powder, resin, UV photoinitiator and wetting agent. After processing on the Optoform ... [more ▼]

Rapid prototyping process called Optoform shapes functional parts from a photocurable paste. This paste contains metal powder, resin, UV photoinitiator and wetting agent. After processing on the Optoform machine, a post-treatment is applied (debinding+sintering). During the post-treatment, the residual carbon coming from the resin modifies the composition of the metal and its melting point. This modification affects densification mechanisms, which leads to a residual porosity that lowers mechanical characteristics. We will present theoretical consideration leading to the optimization of the formulation. To improve the process, bimodal powder is used and thermal treatment is adapted. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailRobustness of a thixoforming production line
Pierret, Jean-Christophe ULg; Rassili, Ahmed ULg; Vaneetveld, Grégory ULg et al

in Solid State Phenomena (2008), 141-143

The development of the thixoforming process made great progress since its beginning. But whereas thixoforming of aluminium and other low melting point alloys is now an industrial reality, thixoforming of ... [more ▼]

The development of the thixoforming process made great progress since its beginning. But whereas thixoforming of aluminium and other low melting point alloys is now an industrial reality, thixoforming of high melting point alloys, as steel, is still at the research level. High temperature issues, die wearing and production rate are problems that must be solved and are more and more investigated. This work is a study of the robustness of a complete thixoforming unit dealing with steel. This flexible unit allows parts of various shapes be formed in conditions close to industrial ones. The study focus on the heating strategy, heat exchanges between the slug and the tool, the feeding and the cycle time. In this work, modelling has been used to simulate heating and feeding. In parallel, experiments have been made to obtain the needed parameters, to validate the modelling and to evaluate the capacities of such a line. [less ▲]

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See detailInvestigation on retained delta ferrite occurrence and its influence on HSS and Semi HSS Strengthening after thermomecanical routes
Tchuindjang, Jérôme Tchoufack ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of Abrasion 2008 (2008)

The present work deals with use of DTA tests in order to understand the crystallisation behaviour of semi-HSS and HSS alloys, and to enhance their solid state transformations. Emphasis is laid on the ... [more ▼]

The present work deals with use of DTA tests in order to understand the crystallisation behaviour of semi-HSS and HSS alloys, and to enhance their solid state transformations. Emphasis is laid on the decomposition of the unexpected retained delta ferrite during thermal and thermomechanical treatment. [less ▲]

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See detailPhysique des matériaux : partim 1 métal
Lecomte-Beckers, Jacqueline ULg

Learning material (2008)

Notions sur le cristal métallique parfait : état liquide, gazeux, solide, forces interatomiques, réseaux cristallins. Propriétés des cristaux métalliques parfaits : propriétés physiques, mécaniques ... [more ▼]

Notions sur le cristal métallique parfait : état liquide, gazeux, solide, forces interatomiques, réseaux cristallins. Propriétés des cristaux métalliques parfaits : propriétés physiques, mécaniques (élasticité-plasticité et rupture), thermiques, électriques. Les imperfections dans les réseaux cristallins : défauts ponctuels, dislocations, polycristaux. Les alliages : les solutions solides (thermodynamique - nanostructure - propriétés), les combinaisons intermétalliques (thermodynamique - propriétés). Diagramme de phases. Applications à des alliages de base (acier-aluminium). Les propriétés mécaniques marquantes des métaux limite élastique, domaine élasto-plastique, rupture, fluage, fatigue) : aspects microscopiques. Structures hors d'équilibre : modifications de la microstructure des métaux au cours de la trempe. [less ▲]

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See detailSélection des matériaux
Lecomte-Beckers, Jacqueline ULg

Learning material (2008)

Description et usage des différents types de matériaux : métaux, céramiques, polymères et composites. Origine et optimisation des propriétés mécaniques et physiques des matériaux. Sélection d'un matériau ... [more ▼]

Description et usage des différents types de matériaux : métaux, céramiques, polymères et composites. Origine et optimisation des propriétés mécaniques et physiques des matériaux. Sélection d'un matériau optimal en fonction des propriétés mécaniques et/ou physiques recherchées. Démarche de sélection du matériau pour une application (haute température, optique,...). Cas pratiques de sélection de matériaux. [less ▲]

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See detailIngénierie des matériaux métalliques: Solidification des métaux et alliages - Traitement thermique
Lecomte-Beckers, Jacqueline ULg

Learning material (2008)

Solidification des métaux et alliages. Traitements thermiques et thermomécaniques des métaux et alliages. Corrosion des métaux. Traitements de surface.

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See detailASSESSMENT OF RETAINED AUSTENITIC PHASE IN INDEFINITE CHILL CAST IRON MICROSTRUCTURE TOWARDS VARIOUS TECHNIQUES
Tchuindjang, Jérôme Tchoufack ULg; Terziev, Liuben; Sinnaeve, Mario et al

Poster (2007, November 16)

Indefinite Chill Cast Irons also called ICDP when used as rolling mill rolls are high alloyed cast iron alloys belonging to the Fe-Cr-C system. ICDP exhibit improved properties regarding hot oxidation and ... [more ▼]

Indefinite Chill Cast Irons also called ICDP when used as rolling mill rolls are high alloyed cast iron alloys belonging to the Fe-Cr-C system. ICDP exhibit improved properties regarding hot oxidation and wear resistances as their microstructure is a mixture of a martensitic with bulky cementite (M3C) and lamellar graphite fully dispersed into the matrix. Mechanical properties involved depend either on the chemical composition of the alloy or the crystallisation behaviour and the heat treatments performed subsequently in order to lead to the desired microstructure. Thus hardenability of the matrix is of great concern as heat treatments sequence is intended to transform austenite in a more stable structure like martensite or even bainite, depending on Cr content. In fact austenite is known to be unstable during hot working conditions as hot temperature and external stresses could yield transformation of this phase into martensite with major volume distortions and even multiple cracks network on the component involved. To avoid such a hitch in service it is quite necessary to make sure all the austenite is completely transformed into martensite while performing subsequent heat treatments like quenching or tempering on the material obtained after casting process. Various techniques are allowable starting from classical ones (X-Ray Diffraction (XRD), Image Analysis, Vibrating Sample Magnetometer (VSM), Dilatometry) to more exotic one like Conversion Electron Mössbauer Spectroscopy (CEMS). From an industrial point of view, it is important to set a fast and reliable method to assess retained austenite presence into ICDP microstructure at the end of any step of the thermomechanical process. The present work is intended to compare different techniques used for retained austenite assessment in ICDP alloys as a first step prior to the calibration of a classical method like dilatometry. This calibration is to be set starting from complex XRD and CEMS spectrometers analyses. Dilatometry seems to overrate retained austenite volume fraction in the as-cast conditions while good agreements are made on the overall batch of techniques when considering heat treated material where retained austenite transformation occurred [less ▲]

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See detailTHIXOFORMAGE DES METAUX: Mise en forme rapide de pièces fonctionelles “near-net-shape” à design complexe dignes du forgeage!
Rassili, Ahmed ULg; Vaneetveld, Grégory ULg; Pierret, Jean-Christophe ULg et al

Poster (2007, June 14)

Présentation du laboratoire de thixofomage de métaux.

Detailed reference viewed: 85 (3 ULg)