Sciences des matériaux

Nombre total de résultats : 417
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Elaboration et caractérisation d'un multimatériau WC-W-Ni obtenu par infiltration: Effet du nickel sur la consolidation du W

BOUCHAFAA Hamida, BOUTAGHOU Zoheir, BOUZEGZI Nourdine, MIROUD Djamel  (2014)
Article de conférence

   En pratique, l’infiltration spontanée de mélanges de poudres libres sous gravité est la plus adéquate à la réalisation des outils de forage. Les pores interconnectés des poudres libres (non compactées) sont remplis avec un métal ou alliage ayant un bas point de fusion. L’attraction capillaire constitue la force motrice de l’infiltration causant la réduction de l’énergie surfacique interfaciale. Le liquide recouvre la phase solide des poudres de la matrice. Les propriétés du consolidé final dépendent étroitement de la composition du mélange de poudres et de sa réactivité avec le liant infiltrant au cours du cycle de frittage imposé.   Nous nous intéressons dans cette étude, pour mieux comprendre les phénomènes qui peuvent se manifester dans le multiconstituant WC-W-Ni (matrice d’outil de forage), àl’élaboration et à la caractérisation du consolidé W-Ni en mettanten évidence l’effet du nickel sur la consolidation de W. Voir les détails

Mots clés : Consolidation, frittage, infiltration, poudres libres, PDC

THE EFFECT OF SUCCESSIVE REPAIRS ON THE WELDMENT QUALITY OF API 5L X 52 STEEL PIPES

B. MAAMACHE, M.BOUABDALLAH, H.BRAHIMI, Y. YAHMI  (2012)
Article de conférence

This work presents the study of the influence of successive repairs on the microstructure and mechanical behavior of the HAZ in a welded HSLA steel API X52. The results show that the succession of repairs in the same area has a direct influence on the microstructure morphology for all the welded joints samples when the mechanical properties by means of tension tests agree well with standards. However, the obtained values of the tensile strength of the various welded pipes are acceptable by the standards which imply the qualification of the welding process for all the repairs. Therefore, the previous investigations lead to the conservation of the same mechanical properties, i.e. the possibility of making more repairs that the standards specify. The grain size of the HAZ obtained after the first repair decrease in impact strength value as the number of repairs increases. Voir les détails

Mots clés : welding, Repair, Heat affected zone

 INFLUENCE DES TRAITEMENTS THERMIQUES A HAUTE TEMPERATURE SUR LA STABILITE STRUCTURALE ET LA DURETE DE L’ACIER DUPLEX 2205

N. OUALI, M. BOUABDALLAH, B. BELKESSA  (2010)
Article de conférence

Les aciers inoxydables jouent un grand rôle dans d'innombrables domaines tel que : l’industrie pétrolière, agroalimentaire, transport, etc. Comme les autres aciers, ce sont des alliages de fer et de carbone auxquels on ajoute du chrome et d'autres éléments, notamment le nickel, mais aussi parfois le molybdène et le vanadium, afin d'améliorer la résistance à la corrosion et d’autres propriétés aussi. Des traitements de mise en solution et de revenu sur l’acier inoxydable duplex 2205 ont montré une sensibilité de cet acier à la précipitation des carbures de chrome et de la phase intermétallique sigma. Ce phénomène apparaît à des faibles temps de maintien et prends un accru lorsqu’on prolonge la durée du vieillissement. Dans le présent travail on montre que la précipitation débute au niveau des joints de grains et se propage à l’intérieur des grains ferritiques provoquant ainsi un durcissement du matériau. Voir les détails

Mots clés : acier inoxydable duplex, traitement thermique, microstructure, précipitation, phase sigma, propriétés mécaniques.

Dynamic mechanical analysis of hybrid composite laminate reinforced with glass/carbon fiber

HALIMI Rafik, BEZZAZI Boudjema, BADIDI BOUDA Ali, ARIBI Choaib  (2014)
Article de conférence

Composite materials possess the characteristics of high stiffness and high fatigue strength, which are desirable for advanced aircraft components. However, the mechanical behavior of such materials depends upon a variety of factors such as fiber volume fraction, percentage of voids, lay-up order and reinforcement type, the effects of which are difficult to establish individually. As the damage initiates in composite materials and grows during static and cyclic loading, material properties such as modulus, residual strength and strain would vary and, in many cases, they may be significantly reduced because of the progressive accumulation of cracks and delaminations. The objective of the current study was to gain a better understanding of mechanical and dynamic mechanical properties of hybrid composite laminate reinforced with glass woven fabric, carbon woven fabric and epoxy matrix, manufactured using vacuum assisted resin molding process. Quasi-static flexural and dynamic mechanical analysis (DMA) tests were conducted on hybrid composites samples prepared according to ASTM standards. Responses of carbon/epoxy and glass/epoxy laminates were also investigated to compare with that of hybrid samples as a function of fiber content. The storage modulus (E’) was found to decrease with temperature in all cases at an oscillating frequency of 1 Hz, and hybrid composite had showed better values of E’ at glass transition temperature (Tg=96°C). Microscopic examinations indicated that flexural failure was mainly due to matrix cracking, shear failure of fiber/matrix interface and delamination. Voir les détails

Mots clés : Composite laminate, hybridation effect, glass transition temperature, dynamic mechanical analysis (DMA)

Damage evaluation in composite laminate by the use of ultrasonic lamb wave

HALIMI Rafik, BEZZAZI Boudjema, BADIDI BOUDA Ali, ARIBI Choaib  (2012)
Article de conférence

This paper presents some ultrasonic methods to detect and to characterize defects, possibly obtained after damage caused in composite materials. Firstly, artificial defects are located by two piezoelectric transducers. A two-dimensional ultrasonic cartography C-scan, performed section by section, at different positions which took part through the thickness of a carbon fiber-reinforced plastic composite beam, to be analyzed. Next, fundamental symmetric S0 mode of Lamb waves is used to measure the size of the delamination by scanning over the surface beneath which a delamination lies. A remarkable decrease in the arrival time due to the delamination is detected, and the delamination length can be calculated based on a simple model for Lamb-wave propagation. Furthermore, the delamination edge is located as a sudden decrease in the amplitude. The rate of decrease in amplitude of an individual pulse cycle was detected to vary with the depth of the delamination, being most sensitive to delaminations near the surface of the plate. This is particularly useful when sizing for defects close to the surface, where a normal-incidence pulse-echo ultrasonic method has problems, particularly when the depth of the defect or the back-wall echoes lie within the length of the transmitted ultrasonic pulse. The technique has potential for faster c-scanning of a complete plate than the usual normal-incidence pulse-echo method. Voir les détails

Mots clés : composite, Ultrasonic C-scan, laminate plate, delamination, Lamb waves

 simulation et étude de la corrosion de la ZATM du procédé FSW d’alliage d’Aluminium 6082 T651

LAABED Abdellatif, ZIOUCHE Aicha, AISSANI Mouloud, IDIR Brahim  (2014)
Article de conférence

Ce travail est un plus à l'étude de la soudabilité de l'aluminium par le procédé FSW. Il présente les microstructures obtenues après la simulation de la zone affecté thermo mécaniquement de la soudure dans un équipement de simulation spécifique. Des observations métallographiques et des mesures de microduretés sont employées comme techniques de caractérisation et ainsi des essais de corrosion.  Voir les détails

Mots clés : FSW, ZATM, AA 6082 T651, corrosion

Mechanical Properties of Fumed Silica/Epoxy Nanocomposite

Saida Mehraz, Boudjema Bezzazi, Nahed Dokhane  (2014)
Article de conférence

The addition of nanoparticles has proven to exhibit a high potential for significantly improving mechanical properties of polymers. This paper aims at the manufacturing and characterization of nanocomposites based on epoxy resin modified with fumed silica nanoparticles. The particles were dispersed into epoxy resin with mechanical mixing and ultrasonic instrument which gave a very well-dispersed phase of nanosilica particles. The resulting degree of dispersion and the interfacial adhesion were investigated by scanning electronic microscopy SEM. Such fumed silica was suspended in an epoxy resin and their rheological properties were measured. Uniaxial Tensile tests under quasi-static and impact conditions performed to evaluate some mechanical characteristics (stress-strain curves, Young’s modulus, yield stress, strain at rupture) of the nanocomposite. Voir les détails

Mots clés : Epoxy, fumed silica, nanocomposite, dispersion of nanoparticles.

Synthesis and characterization of ZnO nanogranules

Saida Mehraz, Nahed Dokhan, Boudjemaa Bezzazi, Ahmed HADDAD, BOUTAGHOU Zoheir  (2015)
Article de conférence

In this paper, we report the synthesis of ZnO nanogranules by a solid state mixing of zinc nitrate tetrahydrate ZnO(NO3)2 with citric acid monohydrate C6H8O7, followed by aging and calcination at different temperatures of 400°C to 600°C. The crystallinity, structure and morphology of as prepared ZnO-nanocrystals have been characterized using powder X-ray diffraction (XRD), scanning electron Microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Optical properties of ZnO nanoparticles were also studied using an ultraviolet–visible (UV–vis) spectrophotometer. Voir les détails

Mots clés : Zinc oxide, nanogranules, ZnO nanopowder.

Effect of ageing time on mechanical properties and microstructural evolution of 2205 ferritic-austenitic stainless steel

N. OUALI, M. BOUABDALLAH, B. BELKESSA  (2012)
Article de conférence

The main of this study is to refine the 2205 duplex stainless steel microstructure using recrystallization process. The adopted way consists in carrying out and optimizing aging heat treatments accompanied by restoring heat treatment.A preliminary treatment of hardening since 1080°C, 1120°C and 1250°C was applied to increase the proportion of ferrite in the matrix. The treatments of aging were performed at the temperature of 850°C during variable duration periods: 30mn, 60mn, 90mn, 02h, 10h, and 30 hours. These treatments modified the structure of the 2205 duplex stainless steel, causing the appearance of a precipitation phenomenon. The precipitates were identified by x-rays diffraction as being the intermetallic  phase, and also the chromium carbides M23C6.This precipitation occurs in the ferrite/ferrite and ferrite/austenite interfaces and propagated inside the ferritic grains. The treatments at 850°C caused a hardening and a remarkable drop of the impact strength of material. The last treatment was carried out at 1080°C during 01 hour, in order to dissolve  phase which precipitate and to restore the / phases balance of the duplex steel. The grains refinement occurred mainly on ferrite; this being with the simultaneous germination of ferrite and austenite during the dissolution of the precipitates. Voir les détails

Mots clés : duplex stainless steel, Recristallization, Precipitation, sigma Phase, Restoring, Toughness impact.

Etude Comparative de l’évolution Métallurgique et Mécanique des Alliages AA6061 - T6 et AA5083 - O après Soudage

HAKEM MAAMAR, LEBAILI SOLTANE, MIROUD Djamel  (2014)
Article de conférence

L’alliage AA6061 T6 est très sensible à la variation de la température due à la précipitation et au phénomène de durcissement structural résultant. A l’opposé, l’alliage AA5083 O ne subit pas de durcissement structural, donc pas de précipitation. Dans le présent travail, l’évolution de la microstructure dans la zone affectée thermiquement d’une part, des essais de traction et de micro dureté ainsi que les faciès de ruptures d’autre part ont été évalués pour les deux alliages.La caractérisation par micro dureté montre que l’alliage 6061 T6 présente une chute de dureté dans de la zone affecté thermiquement, mais l’alliage 5083 O a un profil plus au moins homogène. Les résultats des essais de traction confirment la chute des propriétés mécaniques au niveau de la ZAT de l’alliage 6061 T6. L’étude métallographique montre le changement microstructural des deux alliages après soudage. Des analyses en microsonde EDS mettent en évidence les différents précipités de l’alliage 6061 T6 et les phases de 5083 O. Les faciès de rupture des éprouvettes de traction montrent plusieurs cupules ce qui caractérise la rupture ductile de ces alliages. Voir les détails

Mots clés : soudage, Alliage Aluminium, précipitation.