Sciences et génie des matériaux

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Microstructure and mechanical behavior of dissimilar AISI 304L/WC-Co cermet rotary friction welds

Billel CHENITI, Djamel Miroud, Riad BADJI, Pavol Hvizdoš, Martin Fide, Tamás Csanádi, Brahim BELKESSA, Malik Tata  (2019)
Publication

In this work, dissimilar rapid Rotary Friction Welding of WC-Co cermet to AISI 304L austenitic stainless steel has been conducted using different friction times. The microstructural examination showed that the increase in friction time from 4s to 12s increases the grain size inboth the heat affected zone and the thermo-mechanically affected zone and enlarges the extent of the fully dynamically recrystallized zone. EDS analysis revealed the existence of a Fe-Cr-W rich band along the WC-Co/AISI 304L interface in the central region of the weld joint and its absence from the peripheral region. The formation of this band suggests the occurrence of amutual inter-diffusion between the cermet and the steel which enhanced the metallurgical bonding of the interface. The mechanical behavior investigated by nano-indentation measurements and nano-scratch tests revealed that, regardless the friction time effect and considering the 304 L ASS side, the highest hardness (HIT) and the lowest Young’s modulus (EIT) values were recorded in the fully dynamically recrystallized zone. Besides, the increase of friction time resulted in an increase of hardness and Young’s modulus of each zone in the AISI 304L steel side. Voir les détails

Mots clés : Rotary friction welding, WC-Co cermet, AISI 304L ASS, microstructure, Intre-diffusion, Bonding strength.

Evoltion microstructurale et propriétés mécaniqued'un assemblage WC-Co/Ag-Cu-Zn et WC-Co/WC-W-Ni obtenu parsoudo-brasage

CHENITI Bilal (2018)
Thèse de doctorat

The performance of drilling tools in different conditions is strongly related to microstructural aspect of the hardfacing coating and to the good bonding between the PDC bits and the whole body. In the present work, the manual oxy-acetylene brazing process is employed for the AISI 1020 steel hardfacing using WC-Ni. The Substrate/hardfacing interface and it is performanceusing Ni-Cr-Al-Mo interlayer is particularly studied. The dissolution and the decarburization phenomena of WC particles with the formation of W2C eutectic phase and their effect on the decohesion of WC particles are investigated. On the other hand, and in order to join the PDC bits (WC-Co) to the steel whole body (AISI 1020) and to the matrix whole body of drilling tool (CMM), Sintering by infiltration of loose powder (SILP) process have been employed to elaborate the CMM via a metallic binder of bronze based alloy. Nevertheless, two brazing techniques have been adopted for joining WC-Co to steel and to MMC, the oxyacetylene brazing process, and for the first time, Tungsten Inert gas (TIG) brazing process using Ag based filler alloy. Voir les détails

Mots clés : Infiltration; Brazing; Hardfacing, Interface, microstructure; mechanical properties

Microstructure and mechanical behavior of dissimilar AISI 304L/WC-Cocermet rotary friction welds

B. Cheniti, D. Miroud, R. Badji, P. hvizdos, M. Fides, T. Csanade, B. BELKESSA, M. Tata  (2019)
Publication

In this work, dissimilar rapid Rotary Friction Welding of WC-Co cermet to AISI 304 L austenitic stainless steel hasbeen conducted using different friction times. The microstructural examination showed that the increase infriction time from 4s to 12s increases the grain size in both the heat affected zone and the thermo-mechanicallyaffected zone and enlarges the extent of the fully dynamically recrystallized zone. EDS analysis revealed theexistence of a FeeCreW rich band along the WC-Co/AISI 304 L interface in the central region of the weld jointand its absence from the peripheral region. The formation of this band suggests the occurrence of a mutual inter-diffusion between the cermet and the steel which enhanced the metallurgical bonding of the interface. Themechanical behavior investigated by nano-indentation measurements and nano-scratch tests revealed that, re-gardless the friction time effect and considering the 304 L ASS side, the highest hardness (HIT) and the lowestYoung's modulus (EIT) values were recorded in the fully dynamically recrystallized zone. Besides, the increase offriction time resulted in an increase of hardness and Young's modulus of each zone in the AISI 304 L steel side. Voir les détails

Mots clés : Rotary friction welding, WC-Co cermet, AISI 304L ASS, microstructure, Intre-diffusion, Bonding strength

Stady and analysis of mechanical and viscoelastic behavior in flexure of laminated composites

Rafik HALIMI, Boudjema Bezzazi, Ali BADIDI BOUDA, M’hamed Djelloul Abbou, Oussama Mimouni  (2016)
Publication

In the present paper, seven laminated composites were thesubject of an experimental study to determine their mechanical and viscoelastic properties by means of dynamic mechanical analysis in a bending configuration. The influenceof the frequency, fiber type and fiber orientation on dynamic mechanical properties of different system composites were investigated. Carbon/epoxy laminates exhibit agreat stiffness when fibers are oriented along the axis ofthe clamps, and the maximum modulus was reported forunidirectional carbon/epoxy laminate [08 plies] with56.4 GPa. The glass transition temperature was found to decrease with the incorporation of fibers and increase with increased frequency. For the Kevlar/epoxy laminate, an increase of 12.5 8C in glass transition temperature wasobserved. This is related to a better interfacial adhesion between epoxy matrix and Kevlar fibers. Voir les détails

Mots clés : Composite laminate; Dynamic mechanical analysis; Fiber/matrice interface; Glass transition temperature

Soudage TIG de l’alliage AA2024 et effet du traitement thermique sur les propriétés mécaniques

Youcef SOUAHLIA, Abdelghafour TIFAS  (2014)
Mémoire de Master

Le soudage des alliages d’aluminium présente un intérêt particulier dans le cadre de son application dans diverses industries, automobile, aéronautique et autres.Ce travail consistera à évaluer dans le domaine de soudabilité opératoire, l’influence des paramètres de soudage sur l’alliage AA2024 T3, et les caractéristiques de la soudure. Les évolutions des caractéristiques mécaniques et microstructurales à travers le joint soudé seront déterminées qui sont reliées aux cycles thermiques du soudage par le procédé TIG et les traitements thermiques. Voir les détails

Mots clés : soudage TIG, alliages d'aluminium, Traitements thermiques.

Caractérisations mécaniques et métallographiques d’un joint de soudure réalisé par TIG en acier inoxydable duplex 2205

Bachir-Zakaria DENAIB  (2014)
Mémoire de Master

Notre étude vise la caractérisation mécanique et métallographique d’une soudure autogène dont, le matériau est un acier inoxydable duplex 2205 soudé avec le métal d’apport ER 2209. Ces matériaux de par leurs très bonnes propriétés mécaniques et leurs tenues en milieux corrosifs ainsi que l’aptitude au soudage, ont acquis une importance considérable dans diverses industries. Dans une première partie, nous avons mis en évidence certaines propriétés structurales et mécaniques des aciers inoxydables duplex 2205 (bi-phasé austénite, CFC/ferrite, CC), ainsi que leur évolution structurale suite à une opération de soudage (TIG).Dans une deuxième partie nous avons étudié expérimentalement les caractéristiques mécaniques et métallographiques de l’acier inoxydable duplex 2205. Le comportement de notre acier en traction, délivre des valeurs excellentes sur ces propriétés mécaniques. Le métal de base présente une bonne résistance au choc, même à basse température. Cependant la résistance de zone fondue a sensiblement diminué en raison de la formation de phases dures riches d'austénite secondaires et de la ségrégation inégale des éléments d'alliage. Voir les détails

Mots clés : soudage TIG, acier duplex, Joint de soudure.

Rechargement d’un acier faiblement allié par Soudage TIG et Brasage

Abdelkader AGUIB  (2014)
Mémoire de Master

Ce travail s’intéresse à l’évolution microstructurale de l’interface acier 20NCD2/alliage d’argent allié au nickel obtenue après rechargement par brasage et par soudage TIG, dans le but d’établir un comparatif entre ces deux procédés. Sur la base de profils chimiques établis par EDS (Energy Dispersive Spectrometry), de profils de microdureté HV0.1 et de dureté HV10 nous comparerons l’interface acier/alliage d’apport des échantillons rechargés par les deux techniques considérées. Afin de mettre en évidence, les éventuelles interactions entre les différents constituants de la zone d’adhérence et l’effet thermique des deux procédés. Voir les détails

Mots clés : rechargement, brasage, soudage TIG, interface.

Simplified Modelling of Tandem Cold Rolling

K. SLIMANI, M. ZAAF, H.Bendjama  (2018)
Publication

In this paper, a calculation technique for solving the problem of regulatinginter-stand tension in a tandem cold rolling is proposed. Based on the slicesmethod, the proposed technique develops a computational model for a singlestand, and then generalizes it for five stands. The effectiveness of this technique is evaluated using experimental data acquired from tandem rolling millof IMittal steel complex of El-Hadjar-Algeria. By taking into account theelasticity of the rolls and using Newton’s method; the developed model can beused to calculate, successfully, the tensions correction of the five stands.Compared with the LAM3 software, the obtained results indicated that theproposed technique is effective and can be used to produce better performance of tandem cold rolling. Voir les détails

Mots clés : modelling, tandem cold rolling, slices method, elasticity, Newton’s method.

Image compression of Surface defects of the hot-rolled steelstrip using discrete Cosine Transform and Discrete WaveletTransform

Adel BOUDIAF, Kadri Oussama, Rachid Zaghdoudi, SlimaneZiani, Dehimi Said  (2018)
Article de conférence

Automatic quality control of surface of hot rolled steel using computer vision systems is a real timeapplication, which requires highly efficient Image compression techniques in order to improve the data transmissionand storage capacity.In this work, two image compression methods are simulated. They are Discrete Cosine Transform(DCT) and Discrete Wavelet Transform (DWT).The results of simulation are shown that The Discrete WaveletTransform (DWT) technique given improved result compared with Discrete Cosine Transform (DCT). Voir les détails

Mots clés : Automatic quality control, Computer vision, image compression, Cosine transform, wavelets transform.

Image compression of Surface defects of the hot-rolled steelstrip using discrete Cosine Transform and Discrete Wavelet Transform

Kadri Oussama, Adel BOUDIAF, Rachid Zaghdoudi, SlimaneZiani, Dehimi Said  (2018)
Article de conférence

Automatic quality control of surface of hot rolled steel using computer vision systems is a real timeapplication, which requires highly efficient Image compression techniques in order to improve the data transmissionand storage capacity.In this work, two image compression methods are simulated. They are Discrete Cosine Transform(DCT) and Discrete Wavelet Transform (DWT).The results of simulation are shown that The Discrete WaveletTransform (DWT) technique given improved result compared with Discrete Cosine Transform (DCT). Voir les détails

Mots clés : Automatic quality control, Computer vision, image compression, Cosine transform, wavelets transform