Penetration and microstructure of steel joints by ultrasonic-assisted gas metal arc welding

his work investigates the application of ultrasonic vibration to steel joints formed by gas metal arc welding. Welding is done using a metal active gas welding source with welding current of 120–160 A, 0.8-mm-diameter welding wire and 10 L/min CO2 flow. The distance from the torch to the ultrasonic horn is 120 mm. Ultrasonic vibration most affects the weld when ultrasonic vibration position is 120 mm from torch and increases the penetration when welding speed is 190 (275) mm/min for a 5-mm-thick (10-mm-thick) plate. Moreover, weld width increases when welding speed is 190 mm/min for 10-mm-thick plate. Although ultrasonic vibration does not affect the hardness of welding zones, it modifies the microstructure of the diffusion and welding-pool zones.