GTA welding assisted by mixed ionic compounds of stainless steel

The aim of this study is to evaluate the potential of using gas tungsten arc (GTA) welding assisted by FeS/FeF2 mixtures to improve joint penetration and weld quality in joining 316L stainless steel plates. The differences in surface appearance, geometric shape, and out-of-plane deformation of the weldments made by using conventional and activated GTA welding processes have been compared. The effect of FeF2 on the prevention of undercutting produced by using FeS has also been investigated. The results show that the surface discontinuities in the activated GTA weld metal could be decreased by increasing the concentration of FeF2 in FeS/FeF2 mixtures. The concentration of FeS must be greater than that of FeF2 in order for the joint penetration of GTA weldment to be significantly increased. When FeS/FeF2 mixture was used, the molten metal completely filled the melted-out areas of the base metal, thus eliminating undercutting. The results also show that GTA welding assisted by 75%FeS/25%FeF2 produced a greater increase in the weld depth-to-width ratio, resulting in significant reduction of weld-induced deformation in stainless steel weldments.