Experimental study on controlled pulse keyholing plasma arc welding assisted by ultrasonic vibration

Experimental investigation on controlled pulse keyholing plasma arc welding (PAW) assisted by ultrasonic vibration was carried out. Because of application of the ultrasonic vibration, the peak value of the pulse welding current was decreased by 7–20%, and the welding speed was increased by 17–27% with different base current durations, different current descent times, and different descending currents. It indicates that the ultrasonic vibration can make controlled pulse plasma arc welding achieve stable one-pulse-one-keyhole mode at a lower heat input and a faster welding speed. Under the same welding process parameters, the area of keyhole exit was increased by 38% and the deviation distance of keyhole exit was reduced by 34%. The above results prove that the ultrasonic vibration can reduce the average welding current and heat input, improve the welding efficiency, and enhance the keyholing ability of the plasma arc for controlled-pulse keyholing PAW.