Investigating the Effects of H₂ Additions to Helium and Argon Shielding Gases on TIG-Welded AISI 316L Stainless Steel

Adding hydrogen (H₂) to shielding gas in Tungsten Inert Gas (TIG) welding has garnered attention for its potential to enhance weld quality. This study explores the effects of H₂ and helium (He) content on AISI 316L stainless steel welding, focusing on their influence on weld bead geometry, microstructural properties, and mechanical properties. The H₂ (1.5%, 3%, 4.5%) and He (10%, 20%, 30%) concentrations were evaluated in a shielding gas primarily composed of argon (Ar). The study underscores the need for precise gas blend control to balance enhanced performance with material safety. These findings offer insights into optimizing welding parameters for AISI 316L, with implications for broader applications in industries demanding high quality. The result shows that H₂ (1.5–3.0%) improves penetration, geometry, and surface finish, while He (10–20%) enhances arc stability and smoothness; however, excessive levels of H₂ (>4.5%) cause defects. Optimal mechanical properties (UTS: 714.54 MPa, YS: 449.03 MPa, hardness: 93.34 HRB, impact toughness: 34.45 J) are achieved with 3% H₂, 30% He, and 150 A arc current.