Forming quality, microstructural characteristics and mechanical properties of Al-Li-Cu alloy fabricated by oscillating laser wire additive manufacturing

Fabricating Al-Li-Cu alloy components typically encounters challenges such as coarse grain structures and high porosity. In this work, a circular oscillating laser wire additive manufacturing (OLWAM) process was developed to fabricate thin-walled Al-Li-Cu alloy components. The study investigated the influences of oscillation amplitude and frequency on the distribution of laser energy density. To elucidate the effects of laser oscillation on macro/microstructural evolution, porosity, and mechanical properties, conventional laser wire additive manufacturing (LWAM) was also conducted for comparison. Experimental results demonstrated that the formability was significantly enhanced when the oscillation frequency exceeded 60 Hz. Compared with the LWAM sample, the surface roughness and porosity decreased by 13% and 96%, respectively. In the OLWAM samples, the <100> texture was significantly attenuated, and the average columnar grain size decreased, undergoing a transition into equiaxed grains at the top of the deposition layer. The OLWAM-fabricated Al-Li-Cu alloy exhibited a UTS of 292 MPa and an EL of 12.37%, representing a 35.2% increase relative to the LWAM specimen. This substantial enhancement in strength and ductility is attributed to the synergistic effects of reduced porosity and grain refinement.