Influence of Wire Initial Composition on Anode Microstructure and on Metal Transfer Mode in GMAW: Noteworthy Role of Alkali Elements


Metal Active Gas (MAG) welding in presence of Argon and CO2 mixture as shielding gas is largely developed process allowing the transfer of the liquid metal from the consumable wire anode to th workpiece according to various modes (short-arc, globular, spray-arc). The CO2 presence in the shielding gas leads to the formation of an oxide layer, or gangue, wrapping the droplet, limiting the access to the sptay-mode transfe, taking into account the low conductivity and the high viscosity of tis layer. Several elctrodes of various compositions have been tested thanks to Flux Cored Arc Welding, to limit the gangue formation or its negative contribution, based on Ti, La, Zr and alkali metals addition or reduction in silicon content. The results are interpreted considering the metal transfer mode for a given current intensity (330 and 410 A), wit various CO2 concentrations in the shielding gas. Finally, the role of th gangue, compared to the othr factors governing the droplet detachment, is discussed. A decrease in silicon content limits significantly the gangue formation and gives access to spray arc transfer up to 30 vol.% of CO2 at 330 A. Titanium addition leads to the same results. The tests in presence of zirconium proved te conductivity improvement of the gangue. The addition of alkali allows to stabilize the spray arc up to te noteworthy value of 60 vol.% of CO2 at 330 A, supporting the hypothesis of a strong influence of viscosity on droplets detachment in the process.

Autorzy / Authors: 
F. Valensi, N. Pellerin, S. Pellerin, Q. Castillon, K. Dzierzega, F. Briand, J.-P. Planckaert
Plasma Chem Plasma Process 38: 177.
Tematyka badań: 
Inna tematyka