Magister Thesis

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Etude des mouvements de convection dans un bain fondu d’un matériau soudé avec un laser CO2
(University of M'sila, 2004) Amar, NEKBIL; Enca/A. TAIBI
During the welding of materials with a CO2 laser, the matter in the molten pool is subjected to movements of mixing, or movements of convection. These movements result from the combination of several strengths: strengths of surface tension, viscosity strengths, and gravity strengths. In preceding works the researchers obtained micrographies of weld pool carried out with a CO2 lasers, on various materials (aluminium, steels, stainless steels, titanium). In the work of Taibi Amar, micrographies of some weldings show well the stream lines of these movements. This work relates to the theoretical study of the movements of convection in a weld pool, the explanation of the phenomenon with the detail of the implied forces, the mathematical formulation, i.e. the writing of the equations which control these movements, the solution of these equations by using a software of resolution by finite elements, Flexpde, and finally comparison with the experimental results. This study as any theoretical study pushes towards more results and conclusions, and thus we can deduce the conditions from them to have a privileged direction of rotation of these movements, their effects on the form of the welding, deep or wide, and on the presence of additional components.