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Etude de la contribution des flux activants en soudage A-TIG : application de la silice au soudage de différents métaux et alliages

Abstract : The TIG welding process (Tungsten Inert Gas), extensively used in industry, generates high quality welds by the creation of an electric arc in shielded atmosphere between a non fusible tungsten electrode and the workpiece.
The output of this process is, however, low as the weld penetrations above 3mm become increasing problematic with usual welding parameters.
This work deals with the application of an activating flux to improve the morphology of welded joints. The A-TIG welding (Activated-TIG) allows to strongly increase the penetration of the weld pool by the application of an activating flux on the surface of the workpieces. The depth of weld penetration, limited to 3mm in mono welding pass, can reach 6 to 8 mm depending on base materials and weld positions.
The first part of the study is devoted to optimize the deposit of activating flux. From experimental tests, silica is selected as activating flux for the welding of the 304L stainless steel. The influence of deposit parameters is studied in order to obtain optimized performances.
Subsequently, metallurgical and mechanical investigations are carried out to qualify the molten zone (MZ) and the heat affected zone (HAZ) of the welded structure. In particular, the participation of elements resulting from activating flux in the weld pool leads to chemical and metallurgical modifications. Their identification provides some insight about the advantages and limitations of activating fluxes.
Starting from optimized parameters, the application of silica is extended to the welding of four usual metals and alloys (low carbon steel, commercially pure titanium, commercially pure aluminium and electrolytic copper). The objective of this part is to highlight the activation mechanisms of fluxes according to the welding parametric conditions and the properties of welded materials.
In the last part, the contribution of silica is modelled by two distinct actions; a constriction effect of the electric arc and an inversion of the Marangoni flow. Simple analytical models based on experimental results and deductions are then proposed and implemented in a FEM software.
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https://tel.archives-ouvertes.fr/tel-00011434
Contributor : Guillaume Rückert <>
Submitted on : Monday, March 20, 2006 - 1:15:20 PM
Last modification on : Monday, March 25, 2019 - 4:24:08 PM
Long-term archiving on: : Friday, November 25, 2016 - 10:19:42 AM

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  • HAL Id : tel-00011434, version 2

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Citation

Guillaume Rückert. Etude de la contribution des flux activants en soudage A-TIG : application de la silice au soudage de différents métaux et alliages. Mécanique [physics.med-ph]. Ecole Centrale de Nantes (ECN), 2005. Français. ⟨tel-00011434v2⟩

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