Activated-TIG Welding of Different Steels: Influence of Various Flux and Shielding Gas

Abstract

In tungsten inert gas (TIG) welding, a low depth of penetration (DOP) is achieved during single pass. To achieve the required DOP, the speed of welding should be reduced; thus productivity reduces significantly. In this work, influence of 14 different oxide-, chloride-, and fluoride-based fluxes are evaluated on DOP and width-to-penetration ratio during flux-activated TIG (ATIG) welding of low alloy steel (AISI 4340), austenitic (AISI 304 and AISI 316) and duplex (Duplex 2205) stainless steels. The effect of welding current and three different shielding gas compositions is also studied during ATIG for these workpieces. Arc and weld metal pool behaviors are captured in order to study the physical behavior of the process. Results revealed that oxide-based fluxes like SiO₂, MoO₃, MoS₂, CrO₃, and TiO₂ increases DOP significantly and in many cases through penetration (penetration reaches beyond plate thickness) is achieved. There is a noteworthy enhancement in penetration because of the addition of H₂ in shielding gas. Addition of helium also helps to increase DOP. Arc behavior reveals the constriction of arc column during activated TIG welding, and positive surface tension-induced flow in centripetal (inward) direction is observed.

Keywords:

• Activated flux
• Arc column
• Current
• Depth of penetration
• Shielding gas
• Steels
• TIG

ACKNOWLEDGMENT

The help and support received from Mr. Atul Sharma of Mechanical Engineering Department is sincerely acknowledged.