Influence of Purging Gas on 316L Stainless Steel Fusion Zone in Autogenous Stationary TIG Welding

Abstract

This research reveals the influence of different purging conditions on the fusion zone dimensions and shape for stationary autogenous TIG welding of 316L stainless steel. Welding experiments were performed for unpurged and purged weld root side for 7, 14 and 21 second arcing time. Purging was executed with ten seconds of pre-flow and 23 seconds of post-flow with 10 l/min Ar and 4 l/min of He. Characteristic fusion zone dimensions were extracted and calculated from photo-macrographs of weld cross-sections. Purging the weld root side by argon increased penetration depth and cross-section area compared to helium. Those benefits of argon purging can be attributed to its low thermal conductivity. Measurement of thermal cycles on the weld root side revealed that peak temperatures were higher by argon purging compared to the presence of helium or air. The fusion zone width exhibited no significant differences regardless of weld root side gas type.

Keywords

• argon
• autogenous TIG
• fusion zone
• helium
• penetration
• purging gas, stainless steel 316L