References of "Lecomte-Beckers, Jacqueline"
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See detailEffect of alumina and titanium nitrides inclusions on mechanical properties in high alloyed steels
Lecomte-Beckers, Jacqueline ULg; Tchoufang Tchuindjang, Jérôme; Gfhiri, Rachid et al

in Proceedings of the MSMF-3 International Conference (2001)

every commercial steel product in varying amounts. Since inclusions significantly influence properties and behaviour of materials and at the same time give indications on the quality of the steel, it is ... [more ▼]

every commercial steel product in varying amounts. Since inclusions significantly influence properties and behaviour of materials and at the same time give indications on the quality of the steel, it is quite interesting to precise their nature and their origin. In this paper concerning a project involved in the COST 517 framework, studied alloys are high alloy steels. The raw materials were obtained from the conventionally electrical cast ingot and the Electro Slag Refining processes. The purpose is to compare various inclusions produced by these different processes and their effect on the mechanical properties. The raw material because of the melting processes themselves, leads to a product with a good to a great cleanliness, and tiny inclusions, which are haphazardly distributed. The actual ASTM E45 chart seems to be inappropriate, as the inclusions founded are too small in size. Therefore, we manage to develop a specific procedure for the study of such inclusions. The different types of inclusions encountered are oxides, titanium nitrides, and manganese sulphides. Studying the effect on mechanical properties, oxides often seem to initiate fatigue fracture. [less ▲]

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See detailInfluence of some heat treatments parameters on the microstructure of high alloyed steels
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in Proceedings of the MSMF-3 International Conference (2001)

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See detailEffect of inclusions and grain boundary segregations on the oxidation-corrosion behavior of rolls alloys by electrochemical impedance spectroscop
Perez, F. J.; Duday, D.; Hierro, M. P. et al

in Proceedings of the MSMF-3 International Conference (2001)

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See detailMicroscopic determination of the nature of MC, M2C, M7C3 (M6C) carbides in high speed steels.
Tchuindjang, Jérôme Tchoufack ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of the Annual Meeting of the SBM (société belge de microscopie), Probing the molecular level. (2001)

The present work shows the procedure used to determine the nature of carbides, while using Scanning Electron Microscopy and Energy Dispersive Spectroscopy with X-rays. Then we lay emphasis on optical ... [more ▼]

The present work shows the procedure used to determine the nature of carbides, while using Scanning Electron Microscopy and Energy Dispersive Spectroscopy with X-rays. Then we lay emphasis on optical characterization of carbides. Optical characterization of carbides appear to be the preliminary stage for the general assessment of carbides in HSS microstructure, the final stage of the scheme being the correlation between microstructure parameters (carbides and matrix) and mechanical properties of HSS hot rolling mills rolls. [less ▲]

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See detailImage analysis of carbides in high speed steel rolls and their relationship with the mechanical properties
De Colnet, Laurence; Pirard, Eric ULg; Lecomte-Beckers, Jacqueline ULg et al

in Proceedings of the Euromat Metallographic Conference, Progress in Metallography (2001)

Image analysis is used to describe quantitatively various different natures of carbides in high speed steel rolls. After an etching judiciously selected, the identification and the extraction of the ... [more ▼]

Image analysis is used to describe quantitatively various different natures of carbides in high speed steel rolls. After an etching judiciously selected, the identification and the extraction of the carbide types are based on spectral differences. For every carbide type, three parameters are measure : the size, the spatial distribution and the volume fraction. The size of martensite grain is also measured. [less ▲]

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See detailPerformance characteristics of mill rolls from graphite chromium cast iron
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Breyer, J. P.

in Stal' (2000), 1

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents ... [more ▼]

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite precipitation could contribute to an improvement in thermal conductivity and serve as lubricant preventing sticking. The new material, called graphitic chromium iron, shows good oxidation, wear and thermal behaviour allowing its use as work roll in the last stands of the finishing section of a HSM. In the as-cast condition, graphite precipitation in high Ni and Si chromium cast iron occurs at a temperature of 950 degrees C. Moreover, the amount and volume of free graphite may be increased by secondary graphite precipitation during suitable heat treatment. [less ▲]

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See detailMicrostructure and abrasion resistance of tool steels reinforced by dispersed oxides and carbides phases
Magnée, Adrien ULg; Lecomte-Beckers, Jacqueline ULg

in Revue de Métallurgie- Journées d'Automne de la Société Française de Métallurgie et de Matériaux (2000)

Two ferrous matrix, a high speed steel and a maraging steel were reinforced with alumina, titanium and vanadium carbides. The composite was realized by powder metallurgy. The particles were mechanically ... [more ▼]

Two ferrous matrix, a high speed steel and a maraging steel were reinforced with alumina, titanium and vanadium carbides. The composite was realized by powder metallurgy. The particles were mechanically mixed with the prealloyed powder before compaction. To optimize the composite properties, the processing parameters (i.e. prealloyed powders, size, mixing, conditions, temperature of sintering,...) and the effect of reinforcement (size and composition of particles, volume, fraction,...) were studied. It is necessary to obtain full density with minimum porosity and to control the size, distribution and dispersion of the reinforced particles. The optimal sintering temperature depends on the reinforcement particles used and is of great importance for the properties. Processing parameters (mixing of particles) can greatly affect the final properties. The use of AL2O3 was shown to increases wear resistance in the two matrix. [less ▲]

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See detailLe collage structural : Préparation de surface et durabilité (Corrosion et durabilité des assemblages collés) - Journée d'étude organisée par la SRBII (société Royale Belge des ingénieurs et des Industriels) et le CRIF
Lecomte-Beckers, Jacqueline ULg

Conference (1999, November 03)

L'exposé s'attachera à définir les principaux problèmes liés au phénomène de corrosion dans les métaux. On abordera les différents types de corrosion (corrosion aqueuse, corrosion atmosphérique, corrosion ... [more ▼]

L'exposé s'attachera à définir les principaux problèmes liés au phénomène de corrosion dans les métaux. On abordera les différents types de corrosion (corrosion aqueuse, corrosion atmosphérique, corrosion sèche et corrosion bactérienne). L'accent sera mis sur les phénomènes électrochimiques de base liés à la corrosion aqueuse. On abordera les réactions d'électrodes et de piles du point de vue thermodynamique (diagramme de Pourbaix) et cinétique. On rappellera les différentes formes de corrosion (généralisée, par piqûres, galvanique, caverneuse, intergranulaire, sélective) ainsi que les problèmes couplés de corrosion érosion et de corrosion sous tension. Certains problèmes spécifiques liés aux assemblages collés seront abordés. L'exposé reprendra les différentes possibilités de lutte contre la corrosion. [less ▲]

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See detailPrincipe et utilisation des matériaux (Partim matériaux métalliques)
Lecomte-Beckers, Jacqueline ULg

Learning material (1999)

Objectifs du cours : Donner un aperçu des propriétés des différents matériaux métalliques depuis leur fabrication jusqu’à leur utilisation. Partie matériaux métalliques -chap.1 choix des matériaux et mise ... [more ▼]

Objectifs du cours : Donner un aperçu des propriétés des différents matériaux métalliques depuis leur fabrication jusqu’à leur utilisation. Partie matériaux métalliques -chap.1 choix des matériaux et mise à forme -chap.2 matériaux métalliques- alliages ferreux et non-ferreux -chap.3 physique du métal – propriétés mécaniques des métaux -chap.4 mise en œuvre des matériaux métalliques [less ▲]

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See detailInternational Workshop COST Action 517 : Cleaner for industrial exploitation
Lecomte-Beckers, Jacqueline ULg; Brozova, A.; Eklund, P. et al

Book published by European Commission, Office for Official Publications (1999)

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See detailApplication and performances of graphitic chromium cast iron rolls
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Breyer, J. P. et al

in Revue de Métallurgie [=Revue de Métallurgie. Cahiers d'Informations Techniques] (1999), 96(11), 1401-1411

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents ... [more ▼]

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite precipitation could contribute to an improvement in thermal conductivity and serve as lubricant preventing sticking. The new material, called graphitic chromium iron, shows good oxidation, wear and thermal behaviour allowing its use as work roll in the last stands of the finishing section of a HSM. In the as-cast condition, graphite precipitation in high Ni and Si chromium cast iron occurs at a temperature of 950 degrees C. Moreover, the amount and volume of free graphite may be increased by secondary graphite precipitation during suitable heat treatment. [less ▲]

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See detailCaractéristiques principales des alliages d'aluminium
Lecomte-Beckers, Jacqueline ULg

in Chaire Aluminium organisée par l'Aluminium Center Belgium et le FNRS (1999)

Les propriétés de l'aluminium qui rendent ce métal et ses alliages si attractifs pour de nombreuses applications sont l'apparence, la légèreté, la facilité de fabrication, les propriétés physiques et ... [more ▼]

Les propriétés de l'aluminium qui rendent ce métal et ses alliages si attractifs pour de nombreuses applications sont l'apparence, la légèreté, la facilité de fabrication, les propriétés physiques et mécaniques et bien sûr la résistance à la corrosion. Les applications majeures de l'aluminium peuvent être classées en ordre décroissant de taille de marché et concernent la construction, l'emballage, le transport, les applications électriques, les biens de consommation, les machines et équipements. [less ▲]

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See detailImportance of Heat Treating Procedure in the Study and the Characterization of Impurities in high alloyed Steels
Lecomte-Beckers, Jacqueline ULg; Tchuindjang

in Proceedings of The International COST-517 : Workshop on Cleaner Metals for Industrial Exploitation (1999)

This paper deals with the methodology used in a COST 517 research concerning study of inclusions in high alloyed steel for mechanical purpose. In order to establish in a quantitative and statistically ... [more ▼]

This paper deals with the methodology used in a COST 517 research concerning study of inclusions in high alloyed steel for mechanical purpose. In order to establish in a quantitative and statistically justifiable way the relationship between impurities, inclusions and mechanical properties of high alloyed steels, we have to insure that the microstructure on the whole batch of specimens of the same origin is similar. This required appropriated heat treatments before achieving mechanical tests. Otherwise, metallurgical properties of the samples could vary, and the relationship between inclusions and mechanical properties misunderstood. Regardless of the melting or die atmosphere during the melting, inclusions are present in varying amounts in every commercial steel products. Since inclusions significantly influence properties and behavior of materials and at the same time give indications on the quality of the steel, it is quite interesting to precise their nature and their origin. This requires methods of identifying the inclusions and a knowledge of the history during steel making. [less ▲]

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See detailIntegration of recrystallisation model coupled with an elasto-visco-plastic law - Experimental tests and calibration of this model
Charles, J. F.; Habraken, Anne ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of the 2nd ESAFORM Conference on Material Forming (1999)

The recrystallisation model is based on the model developed by Kopp [1,2]. This model is implemented in our finite element code "lagamine" and is coupled with a thermomechanical elasto-visco-plastic law ... [more ▼]

The recrystallisation model is based on the model developed by Kopp [1,2]. This model is implemented in our finite element code "lagamine" and is coupled with a thermomechanical elasto-visco-plastic law. It assumes that each integration point in the mesh is represented by a number of sub-structures with a different volumic recrystallised fraction. In order to be able to calibrate such a model, we need to perform a lot of experimentals tests. Hot compression tests on small cylinder at different temperatures and strain rates are made till strain level from 0.1 up to 0.7. The compressed cylinders are quenched after the tests. A metallographic study of the quenched cylinders gives the recrystallised fraction function of the strain, the strain rate and temperature. So experimental, numerical and metallographic studies of hot compression tests aim the definition of an accurate predictive thermo-mechanic metallurgical model able to stimulate forging processes. [less ▲]

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See detailUse of graphite chromium cast iron in hot strip mill
Lecomte-Beckers, Jacqueline ULg; Terziev, Luben; Breyer, Jean-Pierre et al

in Proceedings of the Conference SARUC 99 - The Southern African Roll Users Conference (1999)

In this paper, we will point out the good properties of the new material called graphitic chromium iron and show that it can lead to an optimised compromise between oxidation, wear and thermal behaviour ... [more ▼]

In this paper, we will point out the good properties of the new material called graphitic chromium iron and show that it can lead to an optimised compromise between oxidation, wear and thermal behaviour allowing its use as work roll in the last stands of the finishing section of HSM. We will also summarise the results of a study aimed to examine the graphite formation conditions in high chromium iron and the effect of an austenite de-stabilisation heat treatment on the graphitisation. The amount and volume of free graphite may be dramatically influenced by a suitable heat treatment, which increases the thermal properties. Some manufacturing problems associated with the residual stresses of that new grade will also be explained. [less ▲]

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See detailSurface methods for cleaner steels : evaluation of inclusions and grain boundary segregations by electrochemical impedance spectroscopy
Perez, F. J.; Duday, D.; Hierro, M. P. et al

in Proceedings of The International COST-517 : Workshop on Cleaner Metals for Industrial Exploitation (1999)

The structure, defects concentration and the Corrosion resistance of oxide scales formed at 650°C on hot rolling roils composed of HSS steels without or with a 4% Co addition were examined by ... [more ▼]

The structure, defects concentration and the Corrosion resistance of oxide scales formed at 650°C on hot rolling roils composed of HSS steels without or with a 4% Co addition were examined by electrochemical impedance spectroscopy. Scales were obtained aller I , 3 and 6 days of oxidation in air. For ail the steels, Fe203 and Cr203 were mainly formed at the surface. The difference of corrosion behavior is due to the thickness, the microstructure ami the porosity of the scale, which are influenced by the time of oxidation and the Co addition. Corrosion examinations were carried out in a O.5M NaCI solution at ambient temperature. The Co addition has a effect on increasing the corrosion resistance for the non-oxidized and oxidized samples but this effect is limited in tinie. The corrosion increased with die lime of immersion except for the HSS without Co oxidized 3 days. After 6 days of oxidation, the resistarice to COITOSIOfl iS two orders of magnitude higher that means a critical scale thickness was reached. [less ▲]

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See detailEffect of austenite destabilisation heat treatment on graphite precipitation in chromium iron
Lecomte-Beckers, Jacqueline ULg; Terziev, Luben; Breyer, Jean-Pierre

in Proceedings of the International Conference on Solid-SoUd Phase Transformations ‘99 (JIMIC3) (1999)

During solidification of chromium iron, carbides such as M7C3 are precipitating. It is possible to obtain crystallized graphite in the asaCast state by modifying the composition of the alloy[lJ.The aim of ... [more ▼]

During solidification of chromium iron, carbides such as M7C3 are precipitating. It is possible to obtain crystallized graphite in the asaCast state by modifying the composition of the alloy[lJ.The aim of the study is to understanding the mechanism of precipitation of graphite not only during solidification but also during heat treatment. Dilatometric, microcalorimetric, resistometric and microstructural examination methods were used for the investigations. We have shown that graphite precipitation occurs by decomposition ofM7C3 chromium carbides during austenite destabilisation heat treatment. The shape and the amount of graphite depend on the treatment temperature and time. [less ▲]

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See detailStudy and Characterization of Inclusions in Steels obtained from ESR and Conventionally Electrical Ingot Processes
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in Proceedings of the Annual Meeting of the SBM (société belge de microscopie). (1999)

The aim of this research is to establish in a quantitative and statistically justifiable way the relationship between on the one hand, the cleanliness of the steel, the amount of carbides and the ... [more ▼]

The aim of this research is to establish in a quantitative and statistically justifiable way the relationship between on the one hand, the cleanliness of the steel, the amount of carbides and the microstructure of the materials, and then on the other hand their mechanical properties in service. [less ▲]

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