Systematic Welding Process Parameter Optimization in Activated Tungsten Inert Gas (A-TIG) Welding of Inconel 625

This article presents the welding process parameter optimization for activated tungsten inert gas welding of a 6.5 mm thick Inconel 625 plate. The experimental design L-25 has been undertaken to obtain optimal parameters for inputs, including welding current, torch travel speed and arc gap on penetration depth. Welding cross-sectional area, microhardness and welds bead width and bead height have been investigated using various mathematical optimization tools like grey relational analysis (GRA) and Technique for Order Preference by Similarity to Ideal Solution. ANOVA has been used to identify each input parameter's significance. Through bead on trial experimentation, the computed output results of GRA provided the following recommended settings such as 300 A welding current, 90 mm/min Torch travel speed and 5 mm Arc gap as the best optimized parameters. The optimized samples were examined by a scanning electron microscope with energy dispersive X-Ray spectroscopy techniques for a comprehensive study on the laves phase at the interdendritic regions of the weld zone. X-ray diffraction analysis revealed that the major element present in the weld zone was Ni due to which activated flux quickened the solidification rate and reduced laves phase formation.