Quality Enhancement of Laser Powder-Bed Fusion Parts by Acoustically Assisted Additive Manufacturing by Laser Powder-Bed Fusion and its Application to Lattice Structures

Abstract

Additive manufacturing technologies such as laser powder-bed fusion (L-PBF) offer great freedom in design, ultralightweight optimization of components, and individualization of products down to a batch size of one. However, parts fabricated from L-PBF suffer from poor quality. Unavoidable porosity, rough surfaces, anisotropic microstructure, and poor geometrical accuracy and their large scatter pose challenges to post-processing, force larger tolerances, or inhibit technical applications. Acoustic assistance during a build job compacts the powder-bed and has an influence on solidification. This is why the technology addresses all the aforementioned drawbacks. It is known that porosity, surface roughness in downskin regions, and microstructural anisotropy decrease without any post-processing if a build job is sonicated. This study focuses on the fabrication of lattice structures by acoustically assisted L-PBF. Even with a parameter set that is not adjusted to thin-walled structures, porosity decreases in the as-built state. Quasistatic compression tests as well as compressive load increase tests are performed. Results show superior mechanical properties of acoustically assisted samples if compared to standard samples.