The present study investigated longitudinal ultrasonic vibrations applied uniformly perpendicular to the weld line as an efficient approach in the ultrasonic-assisted gas metal arc welding (U-GMAW) of high-strength steel. The penetration depth, microstructure, microhardness, mechanical properties, and corrosion of welded joints produced from GMAW and U-GMAW were experimentally explored at different welding conditions to evaluate their performance. The experimental findings show that welded joints produced by U-GMAW have a maximum ultimate tensile strength (UTS)of 18.7%, while showing 35.4% elongation and 57.4% toughness compared to the GMAW-welded joints at optimal conditions. The surface morphology analysis of the welded joints emphasizes that the dendritic microstructures generated by U-GMAW are finer than the dendritic microstructures generated by GMAW. Moreover, the microhardness of welded joints produced by U-GMAW method is higher than the GMAW-welded joints. The results of the polarization test also confirm that the corrosion rate of GMAW-welded and U-GMAW-welded joints are 360 and 1.60 µm/year, respectively with a power of 30%. These results show that the corrosion rate of welded joints produced by GMAW is much higher than the one produced by U-GMAW.
