Deposition Stability and Forming Characteristics in Laser-Arc Hybrid Additive Manufacturing of Aluminum Alloy Through Beam Oscillation

To overcome the problems of poor stability and forming accuracy in wire arc additive manufacturing (WAAM) of aluminum alloy, laser-arc hybrid additive manufacturing (LAHAM) at different beam oscillating frequencies (f) from 0 to 500 Hz was adopted. The results showed that the LAHAM at f of 300 Hz optimized the droplet transfer during the WAAM from repelled to spray mode, and reduced the transfer time from 5.2 to 3.9 ms. Not only the porosity of deposited thin-wall was decreased from 0.36% to less than 0.01%, but also the average grain size was reduced by 20%. These improvements increased the forming accuracy by 37%, reduced the microhardness fluctuation by 61%, and increased the elongation by 54%. The beam oscillation benefited to reduce the interference caused by droplet impact on molten pool, and form a high-speed rotating vortex to capture the droplets falling into molten pool, thereby improving the deposition stability.