Investigating the effect of different flux combinations, welding current and speed for optimizing D/W ratio in a novel Flux zone TIG welding of SS304

Tungsten inert gas welding is a popular choice for various metal joining operations. However, this application is limited due to shallow penetration. Welding metal that is more than 3 mm thick can significantly increase production costs and time. Flux zone- tungsten inert gas welding provides an essential solution towards the limitation of tungsten inert gas welding by increasing the depth of penetration and depth to width (D/W) ratio. Experimentally, the performance of various flux combinations (TiO₂, SiO₂, Fe₂O₃ centre flux and Cr₂O₃ side flux), welding current (140, 170, 200 amp) and speed (60, 80, 100 mm/min) on the weld surface is evaluated. The response surface methodology of the design of experiment is utilized to develop a second-order mathematical model for the D/W ratio and depth of penetration. The optimized welding parameters is identified as 200 amp current and 64 mm/min welding speed with Fe₂O₃ as a centre flux and Cr₂O₃ as a side flux resulted in 0.965 D/W ratio and a welding current 200 amp, speed 60 mm/min, and flux combination Fe₂O₃ and Cr₂O₃ resulted in 7.941 depth of penetration. It is evidenced from the hardness measurements that a 200 amp current, 60 mm/min welding speed with TiO2 as a centre flux and Cr₂O₃ as a side flux resulted in the highest hardness value of 250.7 HV. A uniform grain structure with a close-pack grain in its flux zone is observed under 200 amp current, 60 mm/min welding speed, with TiO₂ as a centre flux. The findings of the study support the use of this welding technology for joining thick sheets of SS-304 stainless steel for enhanced results.