Abstract
The mechanisms of the inorganic powders, named activating flux and used in ATIG welding process, are not well identified. Oxides and fluorides usually compose activating fluxes. The present paper studies the fluoride activating effect. The analysis of the arc energy influence on the weld bead geometry allows determining the mechanisms that occur during ATIG welding with fluorides. It seems that fluoride activating effect could depends on the fluoride lattice energy and/or the ionic radius of the element. Fluorides act on the arc physics only. An arc energy densification is observed. Furthermore, an arc temperature increase, find out with optical emission spectrometry, characterises the fluoride activating effect. The fluorides do not affect the weld bead surface chemistry. Marangoni convection movements stay centrifugal as in TIG welding and do not favour a penetration increase.
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