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See detailProcessing of carbon fibers reinforced Mg matrix composites via pre-infiltration with Al
Mertens, Anne ULg; Lecomte-Beckers, Jacqueline ULg; Montrieux, Henri-Michel ULg et al

Conference (2011, September)

Mg matrix composites appear as suitable competitors to Al alloys for a wide number of applications, as they allow for a significant weight reduction while exhibiting potentially comparable mechanical ... [more ▼]

Mg matrix composites appear as suitable competitors to Al alloys for a wide number of applications, as they allow for a significant weight reduction while exhibiting potentially comparable mechanical properties. And a large variety of processing routes have already been considered for their production, including 'liquid state' processes such as squeeze casting. These techniques necessitate a very careful control of the wetting behaviour and of the possible interfacial reactions between the reinforcements and the molten metal, along with the solidification process. And this is more particularly true in the case of Mg matrix composites with carbon fibers reinforcements, as Mg alloys are known to exhibit a poor wetting behaviour on carbon substrates. [less ▲]

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See detailInterfacial phenomena in carbon fibre reinforced magnesium alloys processed by squeeze casting and thixomolding
Montrieux, Henri-Michel ULg; Mertens, Anne ULg; Halleux, Jacques et al

Conference (2011, September)

Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibre weaves. Such a material can theoretically exhibit ... [more ▼]

Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibre weaves. Such a material can theoretically exhibit a high yield strength/density ratio. This composite is thought to be especially promising for aeronautics. A pre-treatment of carbon weaves ensure two fundamental functions. The first is to provide stiffness and cohesion. It helps keeping fibres aligned and well placed in the mould during casting to ensure optimal properties of the final part in the main load directions. This is imperative when the composite is formed with thixomolding for which semi liquid metal is injected with a very high speed. Nevertheless the problem of geometrical carbon weaves stability is also encountered with squeeze casting. The second objective of the pre-treatment is to provide a porous network in the weaves to enhance infiltration by the capillary action. The two functions can be assumed by coating fibres with Al(H2PO4)3, SiO2 combined with starch, or some other oxide containing mixtures. The general process is to assemble carbon weaves, infiltrate them in an aqueous solution or dispersion of oxides and lastly heat them at high temperature to promote covalent bonds with fibres and vaporize or crack carbonaceous agents to let a porous medium. Further the chemical interaction between the coated fibres and the liquid metal during infiltration can influence the species which are present at the interfaces. As magnesium oxide is stable magnesium can react with oxides. This could lead to better wettability of treated weave. However such chemical reactions seem to be thermally activated and take many seconds to initiate, whereas solidification of magnesium is achieved faster. Furthermore the addition of some carbide former elements (Si, Ti, Zr) to a magnesium based alloy can also influence chemical affinity. In conclusion CMg-MMC research concerns composites with low density, high potential mechanical properties and possibility of processing through thixomolding. Firstly the reach of the theoretical performance of the composite includes the ability of dealing with the interaction between fibres and liquid metal. Secondly primary treatment could help to form bonds between matrix and fibres, make rigid weaves and promote a further infiltration. Thirdly chemical affinity between the fibres, magnesium alloy and coating can influence the infiltration. [less ▲]

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See detailProceedings of the international conference Abrasion 2011 (Abrasion Wear Resistant Alloyed White Cast Irons For Rolling and Pulverizing Mills), 4th Edition
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

Book published by ULg-Service MMS (2011)

The « Abrasion » Conferences offer an almost unique opportunity to gather every three years people working in the field of abrasion resistant high chromium irons to be used in rolling and pulverizing ... [more ▼]

The « Abrasion » Conferences offer an almost unique opportunity to gather every three years people working in the field of abrasion resistant high chromium irons to be used in rolling and pulverizing mills. The well addresses topic and the small, but very active research community are the key factors for the success of this event. The University of Liege receives the organization by inheritance form Fukuoka (Japan 2002), São Paulo (Brazil 2005) and Trento (Italy 2008). It represents a very tough challenge for the local organizing committee, but the enthusiasm to host in Liege academic staff and people from the industry coming from all around the world was too big to renounce to this opportunity. The number of contributions for this fourth edition confirms that the idea of professor Matsubara to promote the meeting between University and Industry was really responding to the expectations of both these subjects. Scientists and technicians of 12 countries will attend the conference: Austria, Belgium, Brazil, France, Germany, Italy, Japan, Spain, Sweden, Taiwan, Thailand and Turkey. Twenty high quality contributions dealing with solidification, heat treatments, microstructural properties, oxidation and wear resistances will be presented. I believe that the present proceedings will contribute to the extension of knowledge in the area of science, research, development and application in Abrasion Wear Resistant Alloyed Cast Irons for Rolling and Pulverizing Mills. Proceedings are also available in a CD Rom version. A special thanks to all people contributing to the organization of the ABRASION 2011, to the nearby industries Åkers, Arcelor, ESW, GP, Magotteaux, MK, and to the CRM Group for offering the opportunity of the technical visit to the Research plant in Liege. [less ▲]

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See detailInfluence of High Temperature Heat Treatment on in situ Transformation of Mo-rich Eutectic Carbides in HSS and Semi-HSS Grades
Tchuindjang, Jérôme Tchoufack ULg; Sinnaeve, Mario; Lecomte-Beckers, Jacqueline ULg

in Lecomte-Beckers, Jacqueline; Tchuindjang, Jérôme Tchoufack (Eds.) Conference Proceedings of Abrasion 2011 (2011, August)

Alloys of the complex system Fe-Si-C-Cr-C-X, where X is a strong carbide forming-element are well known to exhibit interesting mechanical properties, including wear and abrasion resistances. Such a ... [more ▼]

Alloys of the complex system Fe-Si-C-Cr-C-X, where X is a strong carbide forming-element are well known to exhibit interesting mechanical properties, including wear and abrasion resistances. Such a tribological behavior is mainly due to the presence of carbides especially those obtained during the solidification route and that are known as primary or eutectic carbides. It may therefore be interesting to determine the relative stability of primary carbides when considering thermal and thermomechanical treatments performed at a temperature high enough to allow either the homogenization of the matrix or the occurrence of a desired grain size. This thermal stage is often required to produce tailored microstructures that can lead to improved mechanical properties. In this work a series of thermal treatments performed on samples originated form casting foundry parts were done. Raw materials are both HSS and semi-HSS grades used in application where wear resistance is needed. Thermo- Calc® (TC) simulations and Differential Thermal Analysis (DTA) were performed to determine the crystallization behavior and the subsequent solid state transformations of the studied alloys respectively in equilibrium and in non equilibrium conditions. Light and Scanning Electron Microscopies were done together with hardness measurements in order to enhance metallurgical features of the heat treated samples. Image analysis yielded the determination of carbides volume fractions. It appears from microstructural analyses and carbides quantification that Mo-rich eutectic carbides undergo in situ phase transformations during heat treatments. In fact Mo-rich M2C carbides transform themselves into MC, M6C and M3C, through a so-called budding phenomenon. Such a phenomenon is the evidence of a preferential migration of some atoms that escape from the parent M2C carbide to diffuse further away from their initial site with increasing time and temperature. The stable or metastable nature of eutectic carbides is also discussed from DTA and TC results, as M2C carbides found in both as-conditions and DTA samples were not predicted by equilibrium conditions. [less ▲]

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See detailStudy of the origin of the unexpected pearlite during the cooling stage of two cast high-speed steels
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in Solid State Phenomana (2011), 172-174

Two HSS grades (A and B) belonging to the complex system Fe-Cr-C-Si-X, where X is a strong carbide-forming element such as V, Mb or W, were studied. Samples in the as-received conditions came from an ... [more ▼]

Two HSS grades (A and B) belonging to the complex system Fe-Cr-C-Si-X, where X is a strong carbide-forming element such as V, Mb or W, were studied. Samples in the as-received conditions came from an industrial spin casting process, with a varying cooling rate during processing. Chemical compositions of both alloys were closed to each other and were chosen to enhance their hardenability and to avoid less resistant phases such as pearlite and ferrite. Differential Thermal Analysis was performed on both alloys, in order to increase their crystallization behaviour. Light microscopy and SEM associated with EDS analyses were done to characterize the microstructure of both alloys in the as-received conditions and after DTA trials. The matrix of both HSS grades was composed of eutectic carbides, martensite and retained austenite, these phases exhibiting similar chemical compositions in both alloys. Unexpected pearlite was found in the as-cast HSS alloy B without W, this grade containing more Mo, more V and less Cr than the HSS grade A. It appeared from DTA tests that pearlite found in the alloy B arose more from the destabilisation of the Cr-rich retained austenite associated with the plate-like M2C carbide, than from the matrix itself. In fact, pearlite zones located in the vicinity of M2C are due to related isothermal solid phase transformations form the previous austenitic eutectic phase that is enriched with Cr and Mo. [less ▲]

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See detailMANUFACTURING OF POROUS PARTS IN 316L STAINLESS STEEL BY 3D-PRINTING: SOME INDUSTRIAL CASE STUDIES
Verlee, Bruno; Dormal, Thierry ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of AEPR’11, 16th European Forum on Rapid Prototyping and Manufacturing (2011, June)

Additive technologies offer the possibilities to build complex geometries with integrated functionalities, specific to target application. 3D-printing of metallic powder is an additive technology ... [more ▼]

Additive technologies offer the possibilities to build complex geometries with integrated functionalities, specific to target application. 3D-printing of metallic powder is an additive technology proceeding in 2 steps: a green part is first built layer by layer by printing a liquid binder on the powder bed, and then green part is debinded and sintered. As sintering occurs separately of shaping process, 3D-printing is one of the only additive techniques able to produce porous parts, as filters or other fluid permeable components. Different porous characteristics can be obtained by playing on process parameters (AEPR2010). Several industrial case studies are presented and detailed here with their specifications and characteristics that have been obtained. [less ▲]

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See detailLes matériaux intelligents: pièces à porosité contrôlée en acier inoxydable fabriquées par rapidprototyping
Verlee, Bruno; Dormal, Thierry ULg; Lecomte-Beckers, Jacqueline ULg

Scientific conference (2011, May 24)

Les techniques additives offrent la possibilité de fabriquer des géométries complexes avec des fonctionnalités intégrées spécifiques à l’application visée. L’impression 3D de poudre métallique est une ... [more ▼]

Les techniques additives offrent la possibilité de fabriquer des géométries complexes avec des fonctionnalités intégrées spécifiques à l’application visée. L’impression 3D de poudre métallique est une technique additive procédant en 2 étapes : une pièce verte est d’abord construite couche par couche par impression d’un liant liquide sur le lit de poudre, ensuite cette pièce verte est déliantée et frittée. Comme le frittage se déroule séparément de la mise en forme, l’impression 3D est une des seules techniques additives permettant la fabrication de pièces poreuses, comme par exemple des filtres ou autres composants perméables aux fluides. En jouant sur les différents paramètres du procédé, il est possible de faire varier les caractéristiques poreuses de la pièce finale. La première partie de l’exposé mettra en évidence les effets sur les propriétés finales de paramètres comme la granulométrie de la poudre utilisée, la température et le temps de frittage. La deuxième partie de l’exposé traitera de la fabrication de pièces par impression 3D au départ de mélanges bimodaux de poudre. Le comportement au frittage sera analysé en fonction de la composition du mélange et de sa compacité initiale. Les résultats seront comparés à des modèles trouvés dans la littérature. [less ▲]

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See detailA pendulum test as a tool to evaluate viscous friction parameters in the equine fetlock joint
Noble, Prisca ULg; Lumay, Geoffroy ULg; Coninx, Marc ULg et al

in Veterinary Journal (2011), 188(2), 204-209

An equine fetlock joint pendulum test was studied and the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response examined. Fresh equine digits (group 1, n=6 ... [more ▼]

An equine fetlock joint pendulum test was studied and the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response examined. Fresh equine digits (group 1, n=6 controls; group 2, n=6 lipid solvent) were mounted on a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (τ), viscous damping coefficient (c) and friction coefficient (μ) were monitored for 5h under experimental conditions (400N; 20°C). In all experiments, pendular joint damping was found to follow an exponential decay function (R(2)=0.99714), which confirmed that joint damping was fluid. The evolution of τ, c and μ was found to be significantly (P<0.05) different in the two groups, with a decrease in τ and an increase in c and μ that was faster and more prominent in digits from group 2. It was concluded that pendular joint damping could be modelled by a HOFD model. The influence of post mortem time on results suggested that, ideally, joint mechanical properties should only be tested on fresh cadavers at the same post mortem time. Moreover, the addition of lipid solvent was found to be responsible for upper viscous friction parameters and for a reduced damping time, which suggested that articular lubricating ability was compromised. This equine pendulum test could be used to test the efficacy of various bio-lubricant treatments. [less ▲]

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See detailTowards the Prediction of Damage Of Peritectic Steels During Continuous Casting Process
Keller, Clément ULg; Schwartz, Renée; Bobadilla, Manuel et al

in AIP Conference Proceedings (2011), 1353

In the Continuous Casting process, products are sometimes rejected or called defective due to the presence of transversal cracks. This type of macroscopic damage is expected to be due to a ductility loss ... [more ▼]

In the Continuous Casting process, products are sometimes rejected or called defective due to the presence of transversal cracks. This type of macroscopic damage is expected to be due to a ductility loss during cooling in the bending and unbending areas of the CC line. In order to study this damage, a 2D model has been developed to predict at the mesoscopic level the intergranular crack event taking into account the creep and diffusion of voids. Already validated for a microalloyed steel, the model is identified and used in this study to predict the crack formation for three different grades of peritectic steels. Results show encouraging predictions of the damage. [less ▲]

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See detailEquilibrium and non Equilibrium study of the Fine Pearlite Formation in two Cast High Speed Steels after solidification and thermal treatment
Tchuindjang, Jérôme Tchoufack ULg; Lecomte-Beckers, Jacqueline ULg

in International Journal of Materials Research (2011)

Two High Speed Steels (HSS) have been studied both having chemical compositions closed one to another. Both HSS grades exhibited similar matrix/carbides microstructure in the industrial as-cast conditions ... [more ▼]

Two High Speed Steels (HSS) have been studied both having chemical compositions closed one to another. Both HSS grades exhibited similar matrix/carbides microstructure in the industrial as-cast conditions, except for M7C3 eutectic carbides only observed in one grade and fine pearlite only found in the other grade. Equilibrium diagrams were obtained from Thermodynamical simulations to enhanced predicted phase transformations whereas Differential Thermal Analysis was performed on both alloys in order to determine their crystallization behaviour in non equilibrium conditions. Light microscopy and Electron microscopy associated with microprobe analyses were done to characterize the microstructure of both alloys. Thermal treatments with related bulk hardness assessments were carried out to enhance conditions for pearlite formation at the end of the casting route. In continuous cooling conditions obtained from DTA simulations, the matrix of both as-cast HSS grades is composed of eutectic carbides, martensite and retained austenite, these phases exhibiting similar chemical compositions. The introduction of an intermediate isothermal stage in the solid state within the DTA cooling sequence leads to the formation of a fine pearlite phase mainly located in the vicinity of M2C eutectic carbides on one HSS grade. The origin of this fine pearlite is discussed in this paper. [less ▲]

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See detailNew Trends in Hot Strip Mill Roughing Mills: Characterization of High Chromium Steel and Semi-HSS Grades
Lecomte-Beckers, Jacqueline ULg; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack ULg

in Proceedings of the Iron & Steel Technology Conference (AISTech 2011) (2011)

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an ... [more ▼]

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High-speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions closed one to another, the variation in the alloying elements is intended to assess, on one hand the effect of a small increase of the carbon content, and on the other hand the influence of the addition of a strong MC carbide forming element. The comparison of HCS and semi-HSS grades involves many fields. Regarding the metallurgical aspect, such a comparison led to the enhancement of the solidification range, the crystallization behavior and the microstructure in the as-cast condition for both grades. Furthermore, corrosion behavior and performances of the work rolls in service are compared. Various techniques are used in order to characterize both grades, such as Differential Thermal Analysis (to determine phase transformations temperatures, the crystallization behavior and the interval of solidification), hardness measurements, optical microscopy, scanning electron microscopy associated with energy dispersive X-ray spectroscopy (to determine the nature and the composition of phases, especially matrix and carbides). Finally micro-macro relations between the nature of the microstructure and the properties of HCS and semi-HSS rolls grades in service conditions could be established. [less ▲]

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See detailRECENT TRENDS IN HOT STRIP ROUGHING MILLS: HIGH CHROMIUM STEEL VERSUS SEMI-HSS
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg; Sinnaeve, Mario et al

in Procceedings of the 47th Rolling Seminar - Processes, Rolled and Coated Products (2010, October)

compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new ... [more ▼]

compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions closed one to another, the variation in the alloying elements is intended to assess, on one hand the effect of a small increase of the carbon content, and on the other hand the influence of the addition of a strong MC carbide forming element. Furthermore, corrosion behavior and performances of the work rolls in service are compared. Various techniques are used in order to characterize both grades, such as Differential Thermal Analysis (to determine phase transformations temperatures, the crystallization behavior and the interval of solidification), hardness measurements, optical microscopy, scanning electron microscopy associated with energy dispersive X ray spectroscopy (to determine the nature and the composition of phases, especially matrix and carbides). Finally micro-macro relations between the nature of the microstructure and the properties of High Chromium Steel and semi-HSS rolls grades in service conditions could be established. [less ▲]

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See detailComparison between a high chromium steel and a semi HSS grades used as work rolls in the roughing stands of a hot strip mill
Tchuindjang, Jérôme Tchoufack ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of The 10th International Conference on Steel Rolling (10th ICSR) (2010, September)

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) were compared. The first grade known as High Chromium Steel (HCS) is actually the alloy widely used for such an ... [more ▼]

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) were compared. The first grade known as High Chromium Steel (HCS) is actually the alloy widely used for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve overall properties of the work roll in the roughing stands of the HSM. In the present work, the new semi-HSS grade is studied starting from 3 chemical compositions closed one to another, the variation in the alloying elements being intended to assess, on one hand the effect of a light increase of the carbon content, and on the other hand the influence of the addition of a strong MC carbide forming element. The comparison of HCS and semi-HSS grades involved many fields. Regarding the metallurgical aspect, such a comparison led to the enhancement of the solidification range, the crystallization behavior and the microstructure in the as-cast condition for both grades. Heat treatment behavior of both grades was also investigated and optimal parameters leading to the homogenization of the alloy composition within the deepness of the roll were found. Furthermore, hot corrosion behavior and performances of the work rolls in service were compared. Various techniques were used in order to characterize both grades, such as Differential Thermal Analysis (to determine phase transformations temperatures, the crystallization behavior and the interval of solidification), hardness measurements, optical microscopy, scanning electron microscopy associated with energy dispersive X ray spectroscopy (to determine the nature and the composition of phases, especially matrix and carbides). Finally micro-macro relations between the nature of the microstructure and the properties of HCS and semi-HSS rolls grades in service conditions could be established. [less ▲]

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See detailStability of steel thixoforging process
Pierret, Jean-Christophe ULg; Rassili, Ahmed ULg; Vaneetveld, Grégory ULg et al

in Transactions of Nonferrous Metals Society of China (2010), 20(Special 3), 937-942

Whereas thixoforming of aluminum 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 ... [more ▼]

Whereas thixoforming of aluminum 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 focus on the study of a thixoforming line stability in the aim of industrialization of the process. The line is fully automated in order to maximize the repeatability of the experiments. Studied parameters are the heating cycle, the slug temperature, the tool temperature and the forming speed. For each of them we will give an order of magnitude of the expected variations in a steady-state process as well as the effects of these variations on the process itself (forming load and parts quality). Three different tools, and so three slugs and parts geometries, have been used in the experiments and are presented. Some mathematical simulations have been realized on the finite elements code Forge2008© with a semi-solid constitutive law and are also compared to the experiments. So the capacity of the model to represent the process stability is discussed as well. [less ▲]

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See detailX38CrMoV5 hot-work tool steel as tool material for thixoforging of steel, numerical and experimental evaluation
Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg; Vaneetveld, Grégory ULg et al

in Transactions of Nonferrous Metals Society of China (2010), 20(Special 3), 713-718

Whereas thixoforming of low melting point alloys as aluminum or magnesium is now an industrial reality, thixoforming of high melting point alloys, as steel, is still at the research level. High working ... [more ▼]

Whereas thixoforming of low melting point alloys as aluminum or magnesium is now an industrial reality, thixoforming of high melting point alloys, as steel, is still at the research level. High working temperature, die wearing and production rate are problems that must be solved and are under investigation. The aim of this work is to evaluate the thermal and mechanical loadings applied to the tools during the steel thixoforging process in order to determine if classical hot-work tool steel could be an appropriate tool material. This evaluation has been realized thanks to experimental trials and to simulations on the finite elements code Forge2008©. The effect of the loadings on the tool’s failure modes are highlighted and compared to the ones observed in classical hot forging. Beyond this, the failure modes of hot-work tool steel, the X38CrMoV5 or H11, is presented. [less ▲]

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See detailConception of tooling adapted to the thixoforging of high solid fraction hot-crack-sensitive aluminium alloys
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg et al

in Transactions of Nonferrous Metals Society of China (2010), 20(9), 1712-1718

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<fs<1), which involves the processing of alloys in the semi-solid state. Tooling has to be adapted to this particular ... [more ▼]

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<fs<1), which involves the processing of alloys in the semi-solid state. Tooling has to be adapted to this particular process to benefit of shear thinning and thixotropic behaviour of such semisolid material. Tooling parameters, as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool. These thermal exchanges influence the high-cracking tendency and the rheology of the semisolid material during forming which affect parts properties. This paper shows, thanks to extrusion tests, how thermal exchanges influence surface quality of thixoforged parts made in 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector. A direct application is the evaluation of surface quality of thixoforged thin wall parts made in 7075 aluminium alloys. [less ▲]

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See detailContrôle de la porosité résiduelle dans les pièces en acier inoxydable fabriquées par rapid manufacturing selon la technologie 3D printing.
Verlee, Bruno; Dormal, Thierry ULg; Lecomte-Beckers, Jacqueline ULg

Conference (2010, June 15)

Additive technologies offer the possibilities to build complex geometries with integrated functionalities, specific to target application. 3D-printing of metallic powder is an additive technology ... [more ▼]

Additive technologies offer the possibilities to build complex geometries with integrated functionalities, specific to target application. 3D-printing of metallic powder is an additive technology proceeding in 2 steps: a green part is first built layer by layer by printing a liquid binder on the powder bed, and then green part is debinded and sintered. As sintering occurs separately of shaping process, 3D-printing is one of the only additive techniques able to produce porous parts, as filters or other fluid permeable components. Different porous characteristics can be obtained by playing on process parameters. [less ▲]

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See detailA pendulum test as a tool to evaluate viscous friction parameters in the equine fetlock joint
Noble, Prisca ULg; Lumay, Geoffroy ULg; Coninx, Marc ULg et al

Poster (2010, April)

This study describes an equine fetlock joint pendulum test, and investigates the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response. Fresh equine digits ... [more ▼]

This study describes an equine fetlock joint pendulum test, and investigates the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response. Fresh equine digits (control group 1 (n = 6); lipid solvent group 2 (n = 6)) were mounted in a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (t), viscous damping coefficient (c ) and friction coefficient (µ) were then followed for 5 hours under experimental conditions (400 N; 20 °C). In all experiments, pendular joint damping was found to follow an exponential decay function (R² = 0.99714), which confirms that joint damping is fluid. The evolution of t, c and µ was found to be significantly (P <0.05) different in the two groups. Indeed, t decreased and c and µ increased more rapidly and strongly in the group 2. It was concluded that pendular joint damping can be modelled by an HOFD model. The influence of post mortem time on results suggests that, ideally, joint mechanical properties should only be tested on fresh cadavers at the same post mortem time. Finally, the addition of lipid solvent was found to be responsible for upper viscous friction parameters and for a reduced damping time, which suggests that articular lubricating ability was compromised. This equine pendulum test could be used to test the efficacy of various bio-lubricant treatments. [less ▲]

Detailed reference viewed: 53 (10 ULg)