Efficient manufacturing of Al-Mg alloys using controlled low heat input wire and arc additive manufacturing

Wire and arc additive manufacturing (WAAM) is a cost-effective technique; however, it confronts with excessive heat input resulted from high productivity. Herein, a novel programmable heat input WAAM (PHI-WAAM) is proposed to efficiently manufacture Al-Mg alloys with low heat input. In this method, the total current was dynamically distributed to the cathode wire current, and current of workpiece controlled by an insulated gate bipolar transistor (IGBT). The results indicated that the direct arc and current of workpiece appeared and vanished when the IGBT was switched between turn-on and turn-off states, respectively. In addition, periodic changes were observed in the deflection angles of the droplet trajectory and arc axis. Owing to the decreased current of workpiece, the heat input of the workpiece was reduced by 62.7%, and was precisely diminished via a programmable modified driven signal of the IGBT. The bridging transfer enhanced by an electromagnetic force and spray transfer occurred in the cathode and anode wires, respectively. The productivity was improved by 162.1% using the PHI-WAAM owing to the high melting rates of two wires. The average grain size was decreased from 69 mu m in control group to 38 mu m in PHI-WAAM. It was attributed to the reduced heat input of the workpiece and enhanced stirring effect. The ultimate tensile strength and yield strength were increased by 7.8% and 11.1%, respectively. The PHI-WAAM can fabricate metal parts with controlled low heat input, low cost, high flexibility, and high productivity.