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Genre/Form: | Thèses et écrits académiques |
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Material Type: | Thesis/dissertation |
Document Type: | Book |
All Authors / Contributors: |
Anne Berthier; Pascal Paillard; Université de Nantes (1962-2021).; École polytechnique de l'Université de Nantes.; École doctorale sciences et technologies de l'information et des matériaux (Nantes). |
OCLC Number: | 758940881 |
Description: | 277 p. : ill. ; 30 cm. |
Responsibility: | Anne Berthier ; sous la direction de Pascal Paillard. |
Abstract:
Our work is based on the comprehension and the identification of physical and chemical mechanisms in the molten zone and near the cathode during TIG and A-TIG welding processes. The inversion of convection movements in the melting zone was determined by simple measurements. The electrical arc constriction while passing from TIG to A-TIG was studied using a high speed camera. The optical emission spectroscopy enabled us to quantify the electrical arc temperature and to determine the influence of the activating flux on it. The influence of the welding speed, the arc length and the welding energy on the geometry of the weld bead was demonstrated. The effect of the grain size or the type of deposition of the activating flux on the characteristics of the weld bead is presented. A new flux with similar activating effect than commercial flux but with reduced the toxicity (~30%) was created. A 2D axial symmetric model with a stationary heat source was to simulate the flow behaviour in the melting pool. These results are compared to experiments to validate the results obtained with the numerical model. The deformation of rectangular plates after welding was studied as a function of welding process, the welding speed and the thickness of the plates. The effect of welding parameters on the mechanical properties after welding was demonstrated. The application of the austenitic stainless steel Super Duplex enabled us to show the evolution of the micro structural and mechanical properties and corrosion tests during TIG and A-TIG welding processes.
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