Welding and Control Research Center

Algiers, Algeria

Welding and Control Research Center

Algiers, Algeria
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Hadji Y.,Blida University | Haddad A.,Blida University | Yahi M.,Welding and Control Research Center | Benamar M.E.A.,Blida University | And 6 more authors.
Ceramics International | Year: 2016

Herein we report on the Tungsten Inert Gas (TIG) brazing of Ti3SiC2 to 308 stainless steel and Al brazing fillers materials. The microstructures of the interfaces were investigated by scanning electron microscopy and energy dispersive spectrometry. Intensive interactions including dissolution and diffusion simultaneously occurred within the Ti3SiC2 and at the Ti3SiC2/308 stainless steel interface during TIG-Brazing. The interfacial region between Ti3SiC2 and 308 stainless steel filler is comprised of a decomposed Ti3SiC2 zone, an interaction layer zone and a modified 308 stainless steel zone. When the Ti3SiC2 comes into contact with the 308 SS molten filler during TIG-brazing, it starts decomposing into a TiCx+SiLiquid+Sigas, and simultaneously, deep penetration of the molten 308 SS into the Ti3SiC2 occurred to form a complex bright phase containing [Fe, Cr, Ni, Ti, C, Si] and TiCx phase. The loss of Si is attributed to its evaporation during the TIG-brazing process. Thermally induced residual stress due to thermal expansion mismatches create interfacial cracks between the decomposed Ti3SiC2 and the interaction layer zone. The phases that most likely form when Ti3SiC2 is joined with Al brazed filler material are Al in which some Si is dissolved, TiAl3 and Ti4AlC3. No cracks were observed during TIG joining of Ti3SiC2 with Al brazing filler material. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Halimi M.,Welding and Control Research Center | Ramou N.,Welding and Control Research Center
Journal of Electrical Engineering and Technology | Year: 2012

Non-destructive testing (NDT) is a technique used in science and industry to evaluate the properties of a material without causing damage. In this paper we propose a method for segmenting radiographic images of welding in order to extract the welding defects which may occur during the welding process. We study different methods of level set and choose the model adapted to our application. The methods presented here take the property of local segmentation geodesic active contours and have the ability to change the topology automatically. The computation time is considerably reduced after taking into account a new level set function which eliminates the reinitialization procedure. Satisfactory results are obtained after applying this algorithm both on synthetic and real images.

Temmar M.,Blida University | Hadji M.,Blida University | Hadji M.,Welding and Control Research Center | Sahraoui T.,Blida University | Sahraoui T.,Welding and Control Research Center
Materials and Design | Year: 2011

This paper reports the influence of post-weld aging treatment on the microstructure, tensile strength, hardness and Charpy impact energy of weld joints low thickness 7075 T6 aluminium alloy welded by Tungsten Inert Gas (TIG). Hot cracking occurs in aluminium welds when high levels of thermal stress and solidification shrinkage are present while the weld is undergoing various degrees of solidification. Weld fusion zones typically exhibit microstructure modifications because of the thermal conditions during weld metal solidification. This often results in low weld mechanical properties and low resistance to hot cracking. It has been observed that the mechanical properties are very sensitive to microstructure of weld metal. Simple post-weld aging treatment at 140 °C applied to the joints is found to be beneficial to enhance the mechanical properties of the welded joints. Correlations between microstructures and mechanical properties were discussed. © 2011 Elsevier Ltd.

Ramou N.,Welding and Control Research Center | Halimi M.,Welding and Control Research Center
International Conference on Computer Applications Technology, ICCAT 2013 | Year: 2013

All level set based image segmentation methods are based on an assumption that the level set function is close to a signed distance function (SDF). Small time step and costly re-initialization procedure must be applied to guarantee this assumption, and in order to calculate the gradient, simple numerical schemes, based on finite differences, are applied. In this paper, in order to achieve higher order accuracy in the temporal discretization, we have used Total Variation Diminishing (TVD) Runge Kutta (RK) methods. The spatial derivatives are determined by using the Weighted Essentially Non-Oscillatory methods (WENO-5) that accurately capture the formation of sharp gradients in the moving fronts. In the other hand, we have used the level set method without re-initialization in order to speed up the evolutionary process. Experiments results show that we have obtained good results both on synthetic and real images. © 2013 IEEE.

Bouhouche S.,Iron and Steel Applied Research Unit | Yahi M.,Welding and Control Research Center | Bast J.,TU Bergakademie Freiberg
Applied Soft Computing Journal | Year: 2011

Process monitoring using multivariate statistical process control (MSPC) has attracted large industries types due to its practical importance and application. In this paper, a combined use of principal component analysis (PCA) and self organisation map (SOM) algorithms are considered. Habitually PCA method uses T2 Hoteling's and squared predicted error (SPE) as indexes to classify processes variability. In this paper, new version of indexes called metric distances obtained from the self organisation map (SOM) algorithm replace the conventional indexes proper to PCA. A comparative study between SOM, the conventional PCA and the hybrid form of PCA-SOM is examined. Application is made on the real data obtained from a pickling process. As shown in different figures, the combined approach remains important comparatively to PCA but not more than SOM. © 2010 Elsevier B.V. All rights reserved.

Badji R.,Welding and Control Research Center | Badji R.,University of Paris 13 | Bacroix B.,University of Paris 13 | Bouabdallah M.,E.N.P
Materials Characterization | Year: 2011

The effect of welding and subsequent annealing on the evolution of the crystallographic texture and the anisotropic properties in a 2205 duplex stainless steel was studied. A strong texture was found in the base metal for both austenite and ferrite phases. The austenite texture is composed of rolling (copper and brass) and recrystallization (cube) components whereas the ferrite texture contains mainly a marked < 001>//RD α fibre with a major rotated cube component. The texture evolution during welding and annealing was characterized in the base metal, heat affected zone and weld metal; the corresponding phase proportions and misorientation values were also calculated. The analysis of all these data allows improving the understanding of the recovery, recrystallization and grain growth mechanisms occurring during the various steps of the treatment. Finally, a micromechanical model was used to calculate some mechanical properties from the measured texture, and to confirm that the optimal annealing treatment is about 1050 °C. © 2011 Elsevier Inc.

Badji R.,Welding and Control Research Center | Badji R.,University of Paris 13 | Chauveau T.,University of Paris 13 | Bacroix B.,University of Paris 13
Materials Science and Engineering A | Year: 2013

The deformation behavior of a duplex stainless steel weld joint is studied. A detailed texture analysis shows that the increase of the deformation percentage leads to a reinforcement of all possible {hkl}〈111〉 and {hkl}〈100〉 components in austenite, and of the {hkl}〈110〉 components in ferrite for both the base metal (BM) and the heat affected zone (HAZ). In the weld metal (WM), a strong scatter of the crystallographic orientation relationship (OR) initially found in the solidification microstructure is recorded after deformation. The analysis of the Kernel Average Misorientation (KAM) distribution shows that the deformation is more concentrated in the base metal than in the other parts of the weld joint. The final mechanical behavior studied through microhardness measurement and micromechanical calculations, allows us to separate the contribution of both microstructural and textural evolution to the overall strain hardening of the weld joint. © 2013 Elsevier B.V.

Sami Z.,University of Laghouat | Tahar S.,Blida University | Tahar S.,Welding and Control Research Center | Mohamed H.,Blida University | Mohamed H.,Welding and Control Research Center
Materials Science and Engineering A | Year: 2014

The microstructural changes which occur during intercritical annealing treatment at 780. °C of API X70 High Strength Low Alloy (HSLA) Steel have been investigated. Three treatments were developed to produce dual phase microstructure: Intermediate Quenching Treatment/Air (IQT/A), Intermediate Quenching Treatment/Water (IQT/W) and Step Quenching Treatment (SQT). The IQT/Water treatment resulted in the formation of fine and fibrous martensite morphology uniformly distributed in the ferrite matrix. However, the IQT/Air treatment showed a spherical network of martensite along the ferrite/ferrite grain boundaries. The SQT treatment yielded blocky and banded martensite and ferrite morphology. The experimental results show that the API X70 HSLA steel with finely dispersed microstructures (IQT/Water treatment) has higher Charpy impact properties and lower ductile-brittle transition temperature DBTT than HSLA steel with banded microstructures. A carefully conducted comparison of fracture surfaces of the representative specimens obtained after IQT and SQT treatments has been studied. © 2014 Elsevier B.V.

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