INFLUENCE OF ARGON AND HELIUM PURGING FLOW RATES ON THE FUSION ZONE IN AUTOGENOUS STATIONARY TIG ARC WELDING OF 316L STAINLESS STEEL

The impact of argon and helium purging flow rates of 4 l/ min and 10 l/ min on fusion zone dimensions and shape was investigated. Experiments were perfor med during an autogenous stationary TIG welding process for welding times of 7 s, 14 s, and 21 s. For a welding time of 7 s, the flow rate of the argon and helium purging gases al most did not affect the fusion zone. When the welding time was extended (14 s), the argon purging flow rate also had no significant effect on the fusion zone. However, increasing the helium purging flow rate resulted in a significant (approx. 20 %) increase in weld penetration. Arc time of 21 s and an argon flow rate of 10 l/ min decreased the weld penetration by around 17 %. On the other hand, an increased helium flow rate had the opposite effect, leading to an increase of approx. 17 % in weld penetration.