Abstract: Advanced hybrid heat source has unique advantages in fine control of welding process, microstructure, and performance, and will become the preferred heat source for additively manufactured high-properties aluminum alloy. Aiming at the issues of low stability, high porosity, and low accuracy in the aluminum alloy AM process, a new power modulated oscillated scanning laser hybrid dual pulsed CMT method was proposed. An experimental setup was established, and the experiments were performed. The wire fusion, droplets transfer and mass transfer stability in AM process were analyzed, and the changes of plasma and the temperature in the laser-arc cross area were studied by using spectral and infrared data. The effect mechanism of the laser plasma on the droplet transfer was revealed. The results show that a stable mass transfer and fine regulation process of aluminum alloys AM can be obtained. Using the hybrid heat source, the droplet transfer is complied with the free combined short-circuit transition. When the average current increases from 90 A to 100 A, the diameter of the droplet increased from 1.49 mm to 1.52 mm and transition frequency increased from 74 Hz to 82 Hz. The short-circuit transition frequency is 9 Hz. As the laser power increases from 600 W to 1200 W, the transfer frequency decreases from 70 Hz to 64 Hz, the short-circuit transition frequency is 8 Hz, and droplet’s diameter increases from 1.52 mm to 1.63 mm. The change in the transition behavior of the melt droplet is the result of the combined effect of laser photo-plasma increasing the energy density in the composite zone and the current density in the arc zone, as well as high-speed scanning galvanometer laser dynamically modulating the energy field distribution of the composite heat source.

Key words: aluminum alloy, oscillated scanning hybrid dual pulsed CMT, droplet transfer, temperature field, plasma