Effect of beam oscillating amplitude on forming quality, microstructure, and mechanical performance of Al-Mg-Sc alloy fabricated by laser-arc hybrid additive manufacturing.

• The influence of beam oscillating amplitudes on depositions was studied detailly. • O-LHAM with wide oscillating amplitudes was applied to fabricate Al-Mg-Sc alloy. • The thin wall with sound surface quality was achieved at the amplitude of 4 mm. • Full equiaxed grains were obtained when the amplitude beyond 2 mm. • The optimal mechanical performance was achieved at the amplitude of 4 mm. The oscillating laser-arc hybrid additive manufacturing was applied to fabricate Al-Mg-Sc alloy and the effect of beam oscillating amplitude on macro/micro-morphology and the mechanical properties were investigated in this study. With the oscillating amplitude increased from 0 to 6 mm, the stirring effect of laser beam on molten pool was firstly enhanced due to the expanded active region and then weakened because the laser spot located at the edge of pool. As a result, the improved forming quality, the reduced porosity and the refined microstructures were achieved when the amplitude reached 4 mm, and then negative effect occurred when the amplitude was 6 mm. Eventually, the optimal mechanical performance was achieved at the amplitude of 4 mm and the as-deposited tensile properties reached 353 MPa and 24 % for UTS, and EL in vertical direction, respectively, which were 13.5 % and 50 % higher than that of 0 mm. [ABSTRACT FROM AUTHOR]