References of "Contrepois, Quentin"
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See detailTi alloys processed by selective laser melting and by laser cladding: microstructures and mechanical properties
Mertens, Anne ULg; Contrepois, Quentin ULg; Dormal, Thierry ULg et al

in proceedings of 12th EUROPEAN CONFERENCE ON SPACECRAFT STRUCTURES, MATERIALS & ENVIRONMENTAL TESTING, Noordwijk 20-23 mars 2012 (2012, March)

Selective laser melting (SLM) and laser cladding were developed in the late 1990s as economic layer-by-layer near-net-shape processes allowing for the production – and also, in the case of laser cladding ... [more ▼]

Selective laser melting (SLM) and laser cladding were developed in the late 1990s as economic layer-by-layer near-net-shape processes allowing for the production – and also, in the case of laser cladding, the restoration - of complex parts. Both techniques involve the melting of a metallic powder with a laser. In the case of SLM, the metallic powder is deposited layer by layer and then molten locally according to the desired shape, whereas in laser cladding the metallic powder is projected onto a substrate through a tube coaxial with the laser. In both processes, the metallic melt pools then cool down and solidify very rapidly, thus producing strongly out of equilibrium microstructures that might exhibit high internal stresses. In the present work, efforts have been made to enhance the flexibility of the laser cladding process: a second laser with a maximum power of 300W was installed beside the original laser (with a higher maximum power of 2000W), thus allowing for the processing of parts with thinner walls and/or coatings. Moreover, flexibility was also improved in relation with the geometry of the parts by use of a 5-axes displacement control. Samples of alloy Ti-6Al-4V, that is widely used in the aeronautic industry due to its high specific strength, have been processed both by SLM and by laser cladding. The resulting microstructures have been characterised in details by optical microscopy, SEM and EBSD so as to allow for a better understanding of the solidification process and of the subsequent phase transformations taking place upon cooling for both techniques. The influence of processing parameters such as the orientation of the deposition of the successive powder layers on the mechanical properties was also investigated by means of uniaxial tensile testing performed on samples with different deposition orientations in regard to the direction of mechanical solicitation. Moreover, some of the samples for mechanical testing had undergone an annealing treatment at 640°C for 4 hours to relieve internal stresses, in order to assess more precisely the effect of those stresses on the tensile properties. [less ▲]

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See detailRapidly solidified microstructure of 3D parts fabricated by selective laser melting (SLM) - Examples of stainless steel 316L and titanium Ti-6Al-4V
Contrepois, Quentin ULg; Lecomte-Beckers, Jacqueline ULg

Poster (2011, September 12)

Laser additive manufacturing process capable of producing fully dense metallic parts direct from 3D CAD know a fast development. Major concerns are made to achieve the best accuracy of the final geometry ... [more ▼]

Laser additive manufacturing process capable of producing fully dense metallic parts direct from 3D CAD know a fast development. Major concerns are made to achieve the best accuracy of the final geometry and the reduction of the residual stresses but metallurgical aspects are also essential. The process can be described as a succession of very small welds. A key in the optimization of the mechanical properties is the understanding of the specific solidification mechanisms. Microstructures of two alloys were studied by metallographic examination and EBSD analysis. [less ▲]

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See detailCharacterization of the β Phase Decomposition in Ti-5Al-5Mo-5V-3Cr at Slow Heating Rates
Contrepois, Quentin ULg; Carton Marc; Lecomte-Beckers, Jacqueline ULg

in Open Journal of Metal (2011), 1

The influence of slow heating rates: 2, 5, 10 and 30°C/min (0.033, 0.083, 0.166 and 0.50°C/s) on the β phase decomposition of Ti-5Al-5Mo-5V-3Cr (Ti-5553) during continuous heating were characterized by ... [more ▼]

The influence of slow heating rates: 2, 5, 10 and 30°C/min (0.033, 0.083, 0.166 and 0.50°C/s) on the β phase decomposition of Ti-5Al-5Mo-5V-3Cr (Ti-5553) during continuous heating were characterized by differen-tial scanning calorimetry (DSC) analysis, light microscopy, scanning electron microscopy, X-ray diffraction and hardness testing. Starting microstructure was the β phase obtained by heating the Ti-5553 above the Tβ temperature and a water quench. Results show that heating rate has a significant impact on the precipitation mechanisms and on the β→α transformation in this range of heating rates. The main formation of α precipi-tates occurs between 500 and 600°Cat all heating rates tested. A heating at 2°C/min produces very fine and homogeneously distributed α plate precipitates which have nucleated on the nanometer size ωiso precipitates. The ωiso precipitates between 350 and 400°C. At higher heating rates 10, 15 or 30°C/min, the amount of pre-cipitation of ωiso is lower so an additional formation of nanometer size precipitates occurs between 450 and 500°C. It is supposed that both precipitates act as nucleation sites for α phase precipitation. The resultant mi-crostructure consists in a fine intragranular distribution of α precipitates and a coarser precipitation of α at the grain boundaries. It is shown that the precipitation of ωiso phase retards or prevents the precipitation of nanometer size precipitates occurring between 450 and 500°C. This cannot be generalized to all the β-metastable titanium alloys since Ti-LCB does not exhibit the same heating rate dependence on DSC curves. [less ▲]

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See detailMaterials for advanced power engineering 2010 : Proceedings of the 9th Liège conference
Lecomte-Beckers, Jacqueline ULg; Contrepois, Quentin ULg; Kuhn, F. et al

Book published by Schriften des Forschungszentrum Julich, Reihe energietechnik/Energy Technology Forschungszentrum Julich (2010)

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