Nombre total de résultats : 176
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Simulation and Modeling of Uncertainties in the Calibration of a Fluorescence Chemical Spectrometer (FRX)

S. Djemili, A. HAMOUDA, D. BERDJANE, B. Maalem  (2018)
Article de conférence

Sensitivity analysis and uncertainty estimation are of major importance for the declaration of conformity of finished products. Models must be sought to analyze the test data. The main objective of this work is to establish reliable models to analyze our experimental data and validate them. So we have studied and used the Monte Carlo and Bootstrap simulation methods, we have been able to realize programs that calculate the uncertainty according to the ISO 8466 standard on X-ray fluorescence spectrometer samples from the URASM CRTI chemical analysis laboratory. Programs and interfaces are made with Matlab (GUI). Voir les détails

Mots clés : Simulation; uncertainties; Monte carlo; Bootstrap; calibration

Qualitative and Quantitative Assessment of γ and δ Phases in Duplex Stainless Steel Weldments by the X-Ray Diffraction Technique

A. Kellai, S. Dehimi, M.F. Benlamnouar, S. Kahla, S. Ouallam, Z. Boutaghou  (2018)
Article de conférence

This paper is focused on the quantitative and qualitative characterization of austenitic-ferritic stainless steel welds by the X-ray diffraction technique. The first weldment realized by gas tungsten arc welding process GTAW with ER2209 electrode, the second weldment by shielded metal arc welding process SMAW with E2209-15 electrode. The results show that the presence of two phases, austenite γ and ferrite δ without any precipitation of secondary phases either in the base metal BM or in the two welded zones. Moreover, there is an increase in the ferrite content and the existence of non-uniform compressive stress in the GTAW weld zone. Voir les détails

Mots clés : welding, X-ray diffraction technique, duplex stainless steel, ferrite and austenite

Contribution to the improvement of the quality of continuous casting steels at Sider El-Hadjar-Annaba

Article de conférence

Continuous casting is the process between steel making and rolling. It consists of turning liquid steel into slabs, blooms, or billets. The molten steel comes into contact with the mold, it will solidify and the first phases of the steel will form. This study confirms the need to check the steel quality and the continuous casting parameters such as; casting speed, extraction rate, oscillation of the mold and lubrication during primary cooling. The main objective is to build a thermal model that is an important task for predicting temperature profiles on different sides and edges of the product, in order to optimize the crust of steel. Voir les détails

Mots clés : continuous casting - steel - mold - primary cooling – slab.

Effect of root pass filler metal on microstructure and mechanicalproperties in the multi-pass welding of duplex stainless steels

Ahmed KELLAI, Azzedine Lounis, Sami KAHLA, Brahim IDIR  (2018)

This paper is focused on the estimation of the effect of root pass chemical composition, in multi-pass GTA Weldments, onmicrostructure and mechanical properties of duplex stainless steel welds.We used two different fillermetals, the super duplex ER2594 and duplex ER 2209. Microstructures of different passes of welded joints are investigated using optical microscope andscanning electron microscope. The relationship between mechanical properties, corrosion resistance, and microstructure ofwelded joints is evaluated. It is found that the tensile and toughness properties of the first weldment, employing the combinationof ER 2594 in the root pass and ER 2209 in the remaining, are better than that of the second weldment employing ER 2209 allpasses, due to the root pass grains refinement and its alloy elements content as chromium Cr and nitrogen N. The microstructureindicates the presence of austenite in different forms on the weld zone of ER 2209, same in the case of ER 2594, but with highercontent and finer grains size, in particularWidmanstätten austeniteWA. Potentiodynamic polarization tests of the first weld metalevaluated in 3.5% NaCl solution at room temperature have been demonstrated a corrosion resistance higher than that of thesecond weld metal. This work addressed the improvement of the corrosion resistance using appropriate filler metal withoutgetting any structural heterogeneity and detrimental changes in the mechanical properties. Voir les détails

Mots clés : Gas tungsten arc welding (GTAW), duplex stainless steel, Root pass, Filler metal, Microstructure and mechanical properties


Article de conférence

With the complex examination of raw material from a Sig deposit in Algeria in the region of Mascara area, physical, chemical and mineralogical properties of diatomite have been defined. It has been found that it is a dominantly amorphous material, sedimentary rock of the type silica-diatomite. The raw material consists of approximately 60% SiO2. Of the physical properties, more significant is porosity, which is higher than 60%. The raw material has a wide spectrum of possibilities for practical application: intensive absorbent for several types of liquids and chemical properties of the soil, natural insecticide, and filter water etc. For determination of the chemical contents, properties and origin of the raw material the following methods have been used, such as, chemical analysis, XRD analysis, optical microscopy and thermal analysis. Voir les détails

Mots clés : diatomite, X-ray, XRD, Sig.

Risk of Contamination of the Littoral lands by the mill scale in Annaba City-Algeria

B. Maalem, A. BALASKA, D. BERDJANE, L. Tairi, S. Djemili  (2018)
Article de conférence

A significant amount of scale is produced during casting of ingots and processing of hot-rolled products. In the El Hadjar steel complex, during the various rolling operations, the amount of scale produced is approximately 0.1% of the annual production of the rolling mills. The quality of the thin sheet during rolling is affected by the behavior of the iron oxide layers formed on their surfaces. For this reason, acids and oils are used for the descaling of slabs and billets by means of pressurized water. The calamine, contaminated by these various acids and used oils, is rejected and stored involuntarily on important areas and pollutes soil and groundwater. Micrographic observations as well as x-ray diffraction analysis have shown that calamine consists mainly of iron oxides. Hematite and magnetite become the main components for oxidation times greater than 1 hour. Characterization tests have shown that calamine is dense (ρ = 4.8 g/cm3), its particle size is variable depending on the degree of oxidation (from 0.5 to 10 mm). Simultaneous thermal analysis showed that an increase in mass of the calamine sample with a release of heat. Studies are underway for the physico-chemical characterization of the soils of the storage areas. Voir les détails

Mots clés : Scale, Risks, soil, thermal analysis, granulometry, X-ray diffraction

Infiltration behavior of Cu and Ti fillers into Ti2AlC/Ti3AlC2 compositesduring tungsten inert gas (TIG)brazing

N. Chiker, A. Haddad, Y. Hadji, M.E.A. Benammar, M. Azzaz, M. Yahi, T. Sahraoui, M. Hadj, M.W. Barsoum  (2017)

Herein we study the infiltration behavior of Ti and Cu fillers into a Ti2AlC/Ti3AlC2MAX phase composites using aTIG-brazing process. The microstructures of the interfaces were investigated by scanning electron microscopyand energy dispersive spectrometry. When Ti2AlC/Ti3AlC2 comes into contact with molten Ti, it starts decomposinginto TiCx, a Ti-richandTi3AlC; when in contact with molten Cu, the resulting phases are Ti2Al(Cu)C, Cu(Al), AlCu2Ti and TiC. In the presence of Cu at approximately 1630 °C, a defective Ti2Al(Cu)C phase was formedhaving a P63/mmc structure. Ti3AlC2 MAX phase was completely decomposed in presence of Cu or Ti fillermaterials.The decomposition of Ti2AlC to Ti3AlC2 was observed in the heat-affected zone of the composite.Notably, no cracks were observed during TIG-brazing of Ti2AlC/Ti3AlC2 composite with Ti or Cu filler materials. Voir les détails

Mots clés : MAX phase, Joining, microstructure, hardness, Brazing, TIG process

Effect of Welding Process on Microstructure and Mechanical Properties of Duplex Stainless Steel Welds

A. Kellai, A. LOUNIS, S. Kahla, A. Boutaghane  (2017)
Article de conférence

The purpose of this study is a comparison between the effect of two electrical arc welding processes, on the structural and mechanical behavior of 2205 duplex stainless steel weldments, the first one is the manual process GTAW and the second one is the automatic process SAW. This effect has been identified and examined in the different welding area namely, the base metal BM, the heat affected zone HAZ and the weld metal WM, using optical metallographic techniques and mechanical methods by hardness tests. Voir les détails

Mots clés : duplex stainless steel, welding, microstructure, mechanical properties


R. Benchouieb, D. BERDJANE, S. Achouri, O.GHELLOUDJ, F. LEMBOUB  (2017)
Article de conférence

An approximate model for predicting static recrystallisation of ferritic stainless steel type 430, in hot rolling is proposed. In this model, the effect of variables such as strain, strain rate, temperature and initial grain size were considered during hot rolling operations. A set of integrated mathematical models for predicting static recrystallisation evolution during hot rolling has been developed through laboratory research work experiments. It consists of many sub-models such as percentage of recovery, recrystallisation kinetics, time for 50 percent of recrystallisation, recrystallised grain size and grain growth. Some of the most important theoretic basic approaches to describe the kinetics of primary recrystallisation were first independently developed and comprehensive portrayed by Johnson and Mehl, Avrami as by Kolmogorov (Often named the JMAK-theory).The quantitative determination of the effects of these variables obtained, analysed and compared in the context of the recrystallisation kinetics of this material.The predicted results are in good agreement with measured of laboratory tests. The results of constitutive models based on semi empirical equations will be compared in the next publication to more sophisticated models based on cellular automata, vertex and Monte-Carlo-Potts methods. Voir les détails

Mots clés : ferritic stainless steel, hot rolling, Static recrystallisation, Mathematical model.

Comportement structural et mécanique dessoudures en aciers inoxydables austénitique etduplex réalisées par le procédé TIG

A.KELLAI, A. Boutaghane, B. Boussiala, S. Kahla, S. Dehimi  (2015)

L’objet de cette étude étant de connaître lesdifférentes variations structurales et mécaniques après un cyclethermique de soudage de deux aciers inoxydables de hauteperformance (austénitique AISI 316L et duplex AISI 2205), quisont très utilisés dans tous les secteurs, particulièrementl’industrie pétrolière. On a utilisé le procédé TIG, c’est unprocédé à arc électrique, caractérisé par son apport thermiqueintense et précis aisément automatisé, l’état microstructurale desassemblages soudés a été analysées par des observationsmétallographique optique de différentes zones à savoir : la zonefondue ZF, la zone affectée thermiquement ZAT et le métal debase MB. Finalement les changements microstructurales ont étéargumentés par une filiation de micro-dureté. Voir les détails

Mots clés : Acier inoxydable austénitique, duplex, soudage TIG, micro-dureté et contrôle