References of "Lecomte-Beckers, Jacqueline"
     in
Bookmark and Share    
See detailIdentification of Suitable Steels : Chapter 3
Rassili, Ahmed ULg; Robelet, Marc; Lecomte-Beckers, Jacqueline ULg

in Rassili, Ahmed; Atkinson, Helen (Eds.) Thixoforming steels (2010)

A range of steels is normally industrially available. The question here is to identify those which are most suitable for thixoforming and to adapt the composition to maximise the chances of success. In ... [more ▼]

A range of steels is normally industrially available. The question here is to identify those which are most suitable for thixoforming and to adapt the composition to maximise the chances of success. In this chapter, the influence of alloying elements on the solidus and liquidus temperatures and on the thixoforming window is identified. Some case studies for low and medium carbon steels are given. Thermophysical properties are important for processing and some information is given on the characterisation of these. High carbon chromium steels are another class of steels which are potentially of use. The effect of modifying the Mn and Si content of such steels is described. Thermodynamic prediction is a powerful tool and results from such studies are given. There is then an analysis of the influence of micro-segregation, which results from the original hot rolling, and its interaction with heating speed during the reheating for thixoforming. [less ▲]

Detailed reference viewed: 50 (7 ULg)
Full Text
See detailStudy of Carbon Fibre-Reinforced Magnesium Composites (Introduction to interfacial phenomenon)
Montrieux, Henri-Michel ULg; Lecomte-Beckers, Jacqueline ULg

Conference (2009, November 06)

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

Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibres weaves. Such a material can theoretically exhibit a yield strength/density ratio around 500 compared to ~200 for Ti6Al4V and ~125 for Al2024-T6. This composite is thought to be especially promising for aeronautics if interaction between fibres and magnesium can be controlled and optimized. The strategy studied to enhance interaction between matrix and fibres consists in covering a thin layer of carbide former metal (Zr, Ti) by PVD as a primary treatment of carbon weaves. This intermediate product can then be heated up between 300-700°C in an argon atmosphere in order to form stable carbides. The wetability of treated weaves by liquid magnesium is potentially higher because carbides are not fully covalent (partially metallic) and so they can have more interface interaction with liquid metals. Further crystal lattice parameters of particular carbides can be close to the ones of metal crystal lattices and interface energy can consequently be reduced when they form carbide-metal bonds. Furthermore magnesium is known for its high oxygen attraction and is able to reduce a lot metallic oxides. It is a key fact because liquid magnesium easy wets its oxide in certain conditions. [less ▲]

Detailed reference viewed: 53 (9 ULg)
Full Text
See detailDépôt Laser de poudre à base Fe-C-Mn-Cr et WC/W2C
Montrieux, Henri-Michel ULg; Lecomte-Beckers, Jacqueline ULg

Report (2009)

Le présent rapport concerne l'analyse de dépôts réalisés par Laser Cladding. Ces dépôts sont composés d'une matrice en acier au carbone contenant 13 wt.% de Mn et 14 wt.% de Cr et de granules sphéroïdales ... [more ▼]

Le présent rapport concerne l'analyse de dépôts réalisés par Laser Cladding. Ces dépôts sont composés d'une matrice en acier au carbone contenant 13 wt.% de Mn et 14 wt.% de Cr et de granules sphéroïdales dures à base de WC/W2C métastable. Le rapport met en évidence le phénomène de décomposition du carbure de tungstène. Le carbure décomposé libère du tungstène dans la matrice métallique et provoque la précipitation localisée d'intermétallique Fe-W qui ont une tendance fragilisante. La matrice métallique d'une composition proche de l'acier Hadfield ne semble pas durcir de manière conséquente lors de chocs. La formation de martensite semble donc écartée dans ces conditions. [less ▲]

Detailed reference viewed: 74 (6 ULg)
Full Text
See detailRapid prototyping
Verlee, Bruno; Dormal, Thierry ULg; Clarinval, Anne-Marie et al

Conference (2009, February 25)

In opposition to traditional machining in which part is manufactured by material removal, rapid prototyping techniques allow parts manufacturing by material addition. The part is built layer-by-layer and ... [more ▼]

In opposition to traditional machining in which part is manufactured by material removal, rapid prototyping techniques allow parts manufacturing by material addition. The part is built layer-by-layer and the sum of all layers creates the part. Currently, several techniques exist. They use different kind of materials (metals, ceramics, polymers) and technologies (laser melting, laser polymerising, 3D-printing, cladding, ...). Some of these techniques can deal with nanometric particles. In the case of which a near net shape part is built and must be sintered after shaping, the addition of nano-particles can be useful for sintering by increasing specific surface and reactivity of the batch or by improving the properties of the material. An overview about techniques of rapid prototyping allowing the processing of nanomaterials will be discussed. Tests have been done using Optoform process. This process uses a laser to polymerize a paste made of photo-curable resin loaded with powdered material. Nano-particles can be added and stabilized in the paste. In this presentation, the results obtained with both systems Al2O3 + nano Zr02 and SiC + Nano SiC will be discussed. [less ▲]

Detailed reference viewed: 74 (6 ULg)
Full Text
Peer Reviewed
See detailStructural investigation of solidification and heat treatments influence on High Alloyed Cast Irons Grades with Nb-V-Ti Additions
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in Defects and diffusion forum (2009), 289-292

Two High Alloyed Cast Irons (HACI) were studied, both belonging to the Fe-C-Cr-Si-X system where X was represented by Mo, Nb, Ti or V. One alloy was obtained after adding Nb, V and Ti to the chemical ... [more ▼]

Two High Alloyed Cast Irons (HACI) were studied, both belonging to the Fe-C-Cr-Si-X system where X was represented by Mo, Nb, Ti or V. One alloy was obtained after adding Nb, V and Ti to the chemical composition of the other alloy. Raw materials originated from spun cast rolls for hot strip mill were submitted to different heat treatments routes such as double tempering or quenching, in order to study the influence of alloying elements on the microstructure. Both HACI grades contained a mixture of martensite and retained austenite matrix in the as-cast conditions and after quenching. Differential Thermal Analysis (DTA) was carried out on the heat treated samples in order to determine the phase transformations occurring during re-melting and subsequent solidification sequence. Retained austenite found in the as-quenched HACI without Nb, V and Ti additions exhibited an enhanced stability as confirmed by DTA tests. Various type of martensite were found at the end of heat treatments routes, each having a possible influence on the material behavior while performing re-heating prior to re-austenitisation. Bulky Nb-rich MC carbides precipitating at the beginning of the solidification process strongly influence the nature and the rate of the subsequent phase transformations, particularly for HACI grade with Nb, V and Ti additions. Such NbC carbides were also found to segregate during spin casting process. Quantitative metallography was done to determine graphite, MC carbides, cementite and matrix volume fraction in HACI studied grades. [less ▲]

Detailed reference viewed: 93 (26 ULg)
Full Text
Peer Reviewed
See detailInfluence of the chemical composition on the thixoformability of steels
Pierret, Jean-Christophe ULg; Rassili, Ahmed ULg; Vaneetveld, Grégory ULg et al

in International Journal of Material Forming (2009)

This work deals with the qualification of a variety of steels for their shaping by the thixoforging process. This technology requires setting up a globular microstructure inside the material during ... [more ▼]

This work deals with the qualification of a variety of steels for their shaping by the thixoforging process. This technology requires setting up a globular microstructure inside the material during reheating to a temperature between the solidus and liquidus. As the evolution of the liquid fraction is strongly connected to the steel composition, it is useful to understand how low carbon steel could be alloyed and still thixoformable. The most critical parameter for this is the carbon content. In this study, a theoretical analysis of the phase evolution during the reheating has been performed on the MT Data software to investigate the influence of alloying elements. These first results have been confirmed by Differential Thermal Analysis and by inductive heating experiments on steel slugs. Finally, some parts have been shaped using a thixoforming tool mounted on a hydraulic press. Micrographs of reheated slugs as well as of actual parts are also presented in this paper. [less ▲]

Detailed reference viewed: 36 (10 ULg)
Full Text
Peer Reviewed
See detailBenefits of thixoforging hot-crack-sensitive aluminium alloys at high solid fraction
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg et al

in Proceedings of The 13th Esaform Conference on Material Forming (2010) - semi-solid processing (2009)

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. The use of semi-solid material with globular ... [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. The use of semi-solid material with globular microstructure helps to decrease forming load. But the introduction of a liquid phase in the material is a source of defects that limit mechanical properties of thixoforged parts. One of these defects is the hot cracking for some hot crack-sensitive wrought aluminium alloys. Hot cracking occurs because of strain and deformation during last step of solidification. This paper shows how thixoforging process helps to lower hot cracking tendency without modification of the alloy composition by decreasing strain and deformation due to shrinkage. Different experimental tests by extrusion of 7075 aluminium alloys are used. [less ▲]

Detailed reference viewed: 50 (7 ULg)
Full Text
Peer Reviewed
See detailElectron backscattered diffraction of aluminium alloy 7075 samples after heat treatment
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Lecomte-Beckers, Jacqueline ULg et al

in International Journal of Material Forming (2009)

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. The use of semi-solid material with globular ... [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. The use of semi-solid material with globular microstructure helps to decrease forming load. But the introduction of a liquid phase in the material is a source of defects that limit mechanical properties of thixoforged parts. One of these defects is the hot cracking for some hot crack-sensitive wrought aluminium alloys. Hot cracking occurs because of strain and deformation during last step of solidification. This paper shows how thixoforging process should help to lower hot cracking tendency without modification of the alloy composition by decreasing strain and deformation due to shrinkage. Different experimental tests by extrusion of 7075 aluminium alloys are used. [less ▲]

Detailed reference viewed: 60 (7 ULg)
See detailPhysique des matériaux : partim 2 polymères
Lecomte-Beckers, Jacqueline ULg

Learning material (2009)

Detailed reference viewed: 39 (8 ULg)