Effect of Interlayer Material Thickness on the Weld Quality of Ti-6Al-4 V and Stainless Steel (SS-304) in Automated P-GTAW

Dissimilar welding of titanium alloys and stainless steels is a technologically challenging process primarily due to the formation of brittle intermetallic compounds (IMCs) at the interface, which severely degrades the mechanical properties of the weld. This study investigates the influence of two refractory interlayer materials thicknesses 0.1 mm and 0. 2 mm Niobium (Nb on the weld quality of Ti-6Al-4 V and SS-304 during automated Pulsed Gas Tungsten Arc Welding (P-GTAW). Both interlayers thicknesses were tested using identical welding parameters, and 0.1 mm thick copper filler wire. Tensile testing, Hardness profiling and optical microscopy were conducted to evaluate mechanical performance and microstructural evolution. The results clearly show that the use of thicker interlayer material improved the ultimate tensile strength (UTS) while reducing the formation of brittle intermetallic compounds compared to 0.1 mm Nb. The thicker Nb interlayer (0.2 mm) was found to notably enhance joint strength and microstructural integrity compared to a thinner one, by providing better separation and diffusion control between the dissimilar metals. These findings highlight the crucial role of interlayer material selection in dissimilar metal welding and provides a way toward achieving stronger Ti-steel joints for aerospace and nuclear applications.