Influence of the Activating Flux on Weld Joint Properties at Arc Stud Welding Process

The first papers on the activating flux application appeared already in 1950’s and 1960’s, but the interest for this welding process has been activated again in the last ten years 1, 2 . In order to increase the efficiency and productivity of TIG process, a variant of process with the activating flux is applied (ATIG). With the presence of the activating flux and high temperature, the value of the surface tension of the melted metal is reduced, the electric arc is stabilised and summarised, and the weld bead width is reduced with increased penetration 2, 3 . The activating flux contains activating elements that ensure the necessary weld geometry and modifying elements that refine the weld metal structure (achieving small grained structure) 4 . The activating flux is the mixture of oxide and fluoride metal powders that approve microalloying and modification of the weld metal. It can be produced as a solid chemical substance (powder flux) or as the aerosol spray 3 . Very often, the activating flux is applied as a suspension (solvent of powder flux in acetone or alcohol) that is applied on a surface with a brush or as a spray with 10-20 % acetone. Evaporable liquid, (acetone or alcohol) functions as the solvent. A thin layer of the activating flux is applied on the width of 8-10 mm on both sides of the weld joint. Maximal current density in the electric arc is achieved when there is 4 mg/cm of the activating flux in the welding zone 5 . In order to monitor any possible stability changes at the arc stud welding process, in case of a layer of the activating flux for ATIG process on the surface of the base metal, the results of on-line monitoring of the main welding parameters during arc stud welding with a layer of the activating flux on the base metal, are presented in this paper.