Liste des communications
Modélisation simplifié d’un procédé de mise en forme
La prédiction de l’effort et du couple, des contraintes et des vitesses est indispensable pour conduire de façon optimale une opération industrielle comme celle de laminage. La connaissance préalable de ses grandeurs mécaniques permet la bonne mise au point d’un programme de laminage pour prévoir le bombé des cylindres, le cèdage et une consommation optimale de l’énergie. De grands progrès ont été réalisés ces dernières années dans la mise au point de codes de calculs permettant le développement de cette aspect. La méthode des éléments finis est aujourd’hui la plus utilisée, mais elle demeure lourde et demande un temps de calcul important, ce qui la rend désagréable et peu recommandable pour les industriels qui cherchent des modèles on-line pour piloter leurs opérations. Ce travail présente une contribution répondant à cette dernière exigence. Nous avons commencé par mettre au point un modèle basé sur la méthode des tranches sous environnement MATLAB. Dans la seconde étape, nous avons introduit dans ce modèle l’élasticité des cylindres et la comparaison des résultats obtenus avec ceux tirés de la littérature basée sur la méthode des éléments finis. Voir les détails
Mots clés : modélisation, simulation, Laminage, Matlab, LAM3
SEM/ DRX / EBSD charaterization of electricsubmerged arc welded of an industrial mow carbonsteel
In this study, we tried to understand the impact ofevolution of thermal deformation during the electric submergedarc welding process used to assembling parts. This weldingprocess is applied on an industrial low carbon steel of %C 0.19Wt, %Si 0.25 Wt, %Mn 0.40 Wt, %P 0.025 Wt, %S 0.015 Wt, %Al 0.09 Wt, %Mo 0.009 Wt, %Nb 0.05 Wt and % Ti 0.03 Wt.The plates with thickness of 2.6 mm, it is called BS2. And used bythe company SNS BAG destined for making gas storagecylinders.To highlight the present work, different areas of our specimenswere investigated especially fusion zone and heat affected zone.Characterizations performed are SEM, DRX and EBSD andshow the appearance and texture development during the weldprocess. Note that in this working part, the behavior of thermal Voir les détails
Mots clés : Low Carbon Steel, Electric arc welding, mechanical parameters, textural character formatting
Determination ofresidual stressby X-ray diffractionin a weld cordon
In this study, the implementation of the method fordetermining residual stresses by X-ray diffraction andapply it to the case of a bead of solder. Weldingprocesses induce changes in the microstructure andresidual deformations and stresses that it is so difficultto control that important To study this phenomenonof welding two pieces and low alloy low carbon, werewelded to the electrical arc with coated electrode ofmild steel. The morphology of the samples wascharacterized by optical and electron microscopy,showing the significant change in the microstructurein the different area of the cord. The hardness profilesobtained show that the hardness is stable (200 Hv) inthe base metal and increases in the cord (230 Hv). Inthis work, the X-ray diffraction was used to analyzethe residual stresses. The results of measurements onthe crude sample show that the constraints are allcompression, with a higher level in the side region tothe cord and in the base metal. The relief annealed at650 ° C relaxes the constraints to a lower level whileremaining compressive. These results show that thepresent solder interesting mechanical and structuralcharacteristics, having regard to the present ofresidual compressive stresses, the absence ofstructural defects and cracks. Which promotes goodperformance and long life of the part in its operation. Voir les détails
Mots clés : soudage, contraintes résiduelles, diffraction de rayon X, microscopie.
Study of intermetallic compounds of X182CrN11-1steel hot dipped into molten aluminum
Aluminum coating technique has been applied toimprove high temperature oxidation resistance of steels. Thismethod is adopted widely due to the low cost and goodperformance. The principle of hot-dip aluminizing isaccomplished by immersing materials into molten aluminumbath to form multiple aluminized layers on the surface ofmaterial by atomic inter-diffusion between dipped materials andaluminum. This work focuses on the study of intermetallic layersformed during the hot dip aluminizing of steel with 1.82 %carbon strongly combined with chromium (10.8 %) into a moltenaluminum bath. The X182CrN11-1 steel specimens wereimmersed into molten aluminum at 750°C for 1h, 2h and 3h.Intermetallic compounds were analyzed by optical microscopeand scanning electron microscope (SEM) coupled with energydispersive X-ray spectroscopy (EDS). This study is complementedby microhardness testing.The results showed that hot dip aluminized layer was dividedinto an outer pure aluminum topcoat and an intermetallic layer.This intermetallic layer consisted of an outer FeAllayer and aninner Fe2Al53layer with tongue/finger-like morphology and themicrohardness testing records high values of the intermetallicformed (through the) up to 800Hv0 Voir les détails
Mots clés : aluminizing, intermetallic, diffusion, steel, Microhardness
Phase transition phenomena in an iron phosphateglass and thermal stability criteria
The thermal stability of an iron phosphate glassdedicated to radioactive waste confinement is a crucialcharacteristic for the integrity of the waste package. In this study,we investigate the thermal stability criteria defined by Hruby,Weinberg and Lu/Liu by measuring the glass transitiontemperature (Tg), the crystallization temperature (T), and themelting temperature (T) of an iron phosphate glass loaded withradioactive waste. These temperatures decrease when loading theglass with the waste: Tg decreases from 623.48 °C to 580.04 °C,Tcmfrom 766.34 to 679.26 °C and Tfrom 932.76 °C to 919.75 °C.Thermal stability criteria show satisfactory values, in the interval0.14 0.69. Voir les détails
Mots clés : Iron phosphate glass, Thermal stability, Radioactive waste, XRD, DTA, SEM
Bending of laminated beams using Timoshenkomodel via nonlocal elasticity
In this paper, the bending of laminated beamsusing first order shear deformation theory via nonlocal elasticityis presented. The analysis is presented for static flexure ofsymmetric and anti-symmetric cross-ply laminated beamssubjected to sinusoidal load.Governing equations and boundary conditions are obtainedby using the principle of virtual work.Analytical solutions of bending for simply supportedlaminated beams are presented using this theory to illustrate theeffect of nonlocal theory, and the influence of aspect ratio isexamined. Voir les détails
Mots clés : First-order shear deformation theory; bending, laminated beam, non local
Analytical Characterization of Nd2FeB sinteredmagnet14
The remarkable properties (magnetism andcorrosion resistance)of the Nd-Fe-B sintered magnet areassociated with the presence of other metal elements thatNeodymium-Iron-Boron like Cu, Mn, Al, V, Ni and others. Withan aim of having information on the components in the Nd-Fe-Bmatrix and on the distribution of these elements, in this work, theNAA has highlighted the presence of several metallic elements.Using a mass ratio equal to an activity ratio we can calculate theproportions of detected Elements. The results are: iron with51.30%, neodymium with 25.41% and other elements like nickelwith 1.25%. The rest from the matrix, 22.04%, represents theproportions of B and the other elements traces. In this work weare interested in neutron activation analysis (NAA) in the onlyreason is to identify the metallic Elements in trace (ppm). Voir les détails
Mots clés : NdFeB Sintered magnets, NdFeB characterization, NAA.
Elaboration of Metallic oxide nanopowder Fe dopedZnO
Among the methods of elaboration the metallicoxide nanopowders based on green chemistry,co-precipitation isa simple process used for industrial production in differentsectors .It is the preparation of an aqueous solution containingthe desired cation then mixing with a solution containing theprecipitating agent .the precipitate is then separated from theliquid by filtration, washing, drying and then thermallydecomposing to yield the desired product.Our study focused on pure and Fe doped ZnO nanopowders(Zn1-xFeO, x=0.0,0.005,0.02,0.05 and 0.15)prepared by coprecipitationmethode at room temperature with zinc acetate as azinc source. Samples were analyzed by X-ray diffraction (XRD),scanning electron microscope (SEM), infrared spectroscopy IRand UV-visible spectroscopy.xAll powders are polycrystalline with a hexagonal (wurtzite),grain powders were nanometric sizes. From a doping level thesecondary phase ZnFe2O4 appear and found a decrease in grainsize and increase internal stresses with increasing theconcentration of Fe dopant. SEM images show the existence ofsettlements powder particles in spherical form. IR infraredspectroscopy we identified in the specific vibration and the peakcharacteristic of the ZnO matrix, Zn-O binding was clearlyobserved at around 470 cm-1.the Study of the optical properties ofthe samples clearly shows the doping effect on the opticalabsorption spectra and allowed us to determine the opticalabsorption edge and the width of the gap. Voir les détails
Mots clés : ZnO, ZnFe 2 O, co-précipitation, the structural properties, nanopowder.
First principles study of the new half-metallicferromagnetic full-Heusler alloysCo2CrSi1_xGex: An ab-initio study
We have studied the structural, electronic, elastic,magnetic, thermal and thermodynamic property of thequaternary Heusler alloys Co2CrSi1-xGe(x = 0, 0.25, 0.5, 0.75, 1)with the linearized augmented plane wave method based ondensity functional theory (DFT)and implemented in wien2kcode. For exchange correlation potential we have used thegeneralized gradient approximation (GGA) of Perdew et al. Ourresults provide a theoretical study for the mixed HeuslerCo2CrSi1-xGexx(0
Mots clés : DFT, wien2k, GGA, Heusler, Debye
Effect of cold rolling on texture evolution duringprimary recrystallization of an IF steel
In the present study, we present the effect of cold rolling on texture evolution during primary recrystallization of an IF steelthat is destined to the automotive industry. From the hot rolled sheet, three deformation rates were performed by cold rolling: 25, 50and 75 % followed by several heat treatments in order to obtain the fully recrystallized states. Microhardness Vichers was used toestimate the recrystallized fraction and XRD (X-ray diffraction)for the texture characterization. The results show that texture of thehot rolled sample is near random and its evolution is very low for the 25% reduced sample. However, texture become more importantfor 50% and 75% reduces states, with the strengthening of -fiber and the appearance of -fiber. The evolution of texture duringprimary recrystallization is quite different. Recrystallization of the 25% and 50% cold rolled states shows a maximum of the ODF on{223}<110> component and texture tends generally to be random. The recrystallization texture of the 75% reduced sample ischaracterized by a -fiber more intense than - fiber and a maximum of the ODF around the component {111}<110>. It was observedalso that -fiber starts to develop during the primary recrystallization of the 50% rolled state, and becomes more pronounced duringrecrystallization of the 75% cold rolled sample. Voir les détails
Mots clés : IF steel, Cold rolling, primary recrystallization, texture, XRD, -fiber, -fiber.