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Soudage par résistance des tôles fines revêtues : formation du noyau dans un assemblage de trois tôles

Abstract : In the automotive industry, the requirements for polluting emissions lead to light vehicles, especially in decreasing the steel sheet thickness. This work in partnership with ArcelorMittal focuses on resistance spot welding of steel sheets. The aim is to identify the phenomena that induce operating weldability difficulties encountered with an asymmetrical stack of three coated steel sheets, including a very thin galvanized sheet of less than 0.6 mm, a sheet of DP600, and a hot stamped Usibor® sheet. Infrared camera observations show that the initial heating takes placeat the interfaces with the Usibor®1500 sheet, and that the nugget appears inside this sheet, away from the thin sheet. The very high values of the electrical and thermal contact resistances, measured at the interfaces with the Usibor®1500 sheet, are due to the Alusi® coating and are at the origin of the strong initial heating at these interfaces. A numerical model, limited to the electro- thermal aspects and developed with COMSOL Multiphysics®, shows that the nugget is initiated very quickly in Usibor®1500 sheet under the effect of adjacent contact resistances, and that its development is driven by the evolutions of the electrode-sheet contact areas. The contact resistances between the electrode and the thin sheet, the welding current evolution, and the curvature radius of electrode tips are the most efficient parameters to be optimized to improve the penetration of the nugget in the thin sheet.
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https://tel.archives-ouvertes.fr/tel-01960707
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Submitted on : Wednesday, December 19, 2018 - 3:15:09 PM
Last modification on : Friday, September 25, 2020 - 3:36:04 AM
Long-term archiving on: : Wednesday, March 20, 2019 - 10:52:40 PM

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  • HAL Id : tel-01960707, version 1

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Edouard Geslain. Soudage par résistance des tôles fines revêtues : formation du noyau dans un assemblage de trois tôles. Mécanique [physics.med-ph]. Université de Bretagne Sud, 2018. Français. ⟨NNT : 2018LORIS481⟩. ⟨tel-01960707⟩

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