Effect of TiO₂ Crystalline Phase on Performance of Flux Assisted GTA Welds

Abstract

Rutile and anatase TiO₂ fluxes were used to investigate the influence of the powdered oxides on the joint penetration ability (JPA) and solidification cracking susceptibility (SCS) in the gas tungsten arc (GTA) welding of type 316L stainless steel (SS). The mechanisms underlying the increase in JPA of GTA welds made with various crystalline phases of TiO₂ were also identified. The results indicate that GTA welding with rutile TiO₂ (R-TiO₂) or anatase TiO₂ (A-TiO₂) forms a viscous slag over the surface of the weld. The R-TiO₂ is more thermodynamically stable than the A-TiO₂, leading to a greater improvement in JPA of GTA weld made with A-TiO₂. The welding arc action can be ignored and only the convection of the molten pool should be considered in the underlying mechanism for the increase in JPA of GTA weld made with R-TiO₂ or A-TiO₂. Moreover, the TiO₂ assisted GTA welding of type 316L SS was effective in decreasing the SCS.

Keywords:

• Additives
• Anantase
• Flux
• Oxide
• Powder
• Rutile
• Titania
• Welding