Improved formation accuracy and mechanical properties of laser-arc hybrid additive manufactured aluminum alloy through beam oscillation

High-frequency circular beam oscillation was employed for the laser-arc hybrid additive manufacturing of AA4047 aluminum alloy. Under the optimized oscillating frequency of 300 Hz, the effects of oscillating diameter (D) on the forming accuracy, microstructure and mechanical properties of deposited thin-walls were studied. It was found that the effective forming width reached a maximum of 88.9 %, and the porosity decreased from 0.1 % to 0.01 % when the D increased from 0 to 1.2 mm. Furthermore, the machining allowance was reduced from 1.51 to 1.25 mm, which indicated that the formation accuracy was improved by 17 %. The increasing D reduced the average size of grains from 55.9 to 44.8 mu m, showing a refinement degree of 19.9 %. These improvements reduced the microhardness distribution variance of thin-wall from 31.82 to 13.37. The ultimate tensile strength increased from 219.1 to 227.3 MPa, and the elongation increased from 12.9 % to 14.6 %. Based on the high-speed camera observation, the study discussed the influence of laser beam oscillation on the droplet transfer and melt flow behavior, as well as the improvement mechanism of deposition quality.