Controlling surface finish in critical areas for additive manufacturing high-quality aerospace components by laser-based powder bed fusion (L-PBF) process

Additive manufacturing of critical aerospace end-products using advanced laser-based powder bed fusion (L-PBF) technology is promising, given the possibility of reducing the weight of 3D objects and producing components with complex internal channels and fine structures that cannot be reproduced by any other manufacturing method. Given the strict requirements for aircraft/engine components, the surface quality of complex-shaped parts manufactured by L-PBF does not meet the requirements. On the other hand, it requires significant effort and costs in post-processing. As a result, the surface finish improvement in critical areas for the production of high-quality aerospace parts by LPBF is very relevant in the additive manufacturing route. In this work, the support-free Inconel 718 alloy structures were laser powder bed fused with a layer thickness of 60 µm through customized LPBF build strategies using a Python-based recipe framework, a Renishaw RenAM 500Q machine, and gas-atomized powder with a nominal particle size in the range of 15–55 μm. The laser power and scanning speed were varied in the critical downskin/overhang regions to control the laser energy, allowing for supplying the different volumetric energy density (VED, J/mm3) in the hatch spacing and linear energy density (LED, J/mm) in the contour as compared to the unmodified region. The unmodified and modified downskin/overhang surface topographies in the as-built samples were examined using an Alicona InfiniteFocusG5 optical 3D measurement system. The results demonstrated that customized build strategies in the L-PBF process enable the assignment of different laser parameters and hatch strategies across complexly-shaped Ni-based alloy parts, thereby improving thermal management and, correspondingly, controlling the surface quality in the downskin regions. Compared to support-free Inconel 718 alloy structures manufactured using a standard method, the quality of the programmable modified regions on the part was obtained more uniformly and consistently across the entire build plate.