Analyzing weld bead geometry and microstructure in ultrasonic-assisted activated flux TIG welding of ST37 steel

In this study, activating gas tungsten arc welding (A-GTAW) have been successfully done using ultrasonic vibration-assisted (UV-A) on bead-on-plate and butt weld ST37 steel. High-intensity acoustic waves were generated by a high-frequency ultrasonic generator operating at a frequency of 20 kHz and different amplitude. These waves were introduced into the molten weld pool through a suitable horn. The impact of UV-A and nanoparticles on the geometry and microstructure of the weld zone was analyzed and compared with the conventional gas tungsten arc welding process. The results revealed that the use of SiO₂ nano-sized activating flux in conjunction with acoustic waves in bead-on-plate welds not only increased weld penetration by approximately 58% but also reduced the weld bead width (WBW) by 22% and enhanced microhardness by 35.5% compared to conventional Tungsten Inert Gas (TIG) welding. Also, changes incomplete penetration in butt joint to full penetration. Furthermore, this combined approach exhibited a significant influence on refining the grains in the welded material.