Flux Bounded Tungsten Inert Gas Welding (FBTIG)
Flux-assisted welding techniques were a breakthrough in tungsten inert gas welding, which increased the weld penetration significantly. Although activated tungsten inert gas (ATIG) welding was initially proposed, its shortcomings such as the necessity of automation and the possibility of entrapment of flux particles in the weld bead hindered its commercialization. Sire and Marya proposed an alternative, flux bounded tungsten inert gas (FBTIG) welding, in which the activating flux is applied on the base metal leaving a narrow ‘flux gap’ along the weld line. In addition to the reversed Marangoni convection currents and the arc constriction effect active in ATIG welding, the insulation effect is also relevant here. This process has proved to overcome the disadvantages of ATIG welding while retaining its advantages. Apart from the general welding parameters such as welding current or welding speed, parameters such as the nature of flux, flux gap, flux particle size, flux coating density etc. are relevant in FBTIG welding.