Microstructure and mechanical properties of a closed impeller fabricated via LPBF employing a supportless printing approach

Laser powder bed fusion (LPBF) has enabled the fabrication of geometrically complex parts for various applications. The complex design of a closed impeller inheriting overhang features below 45° angle with the reference of build direction is commonly fabricated with a series of support. The used supports are later removed during post-processing; however, the support removal for the internal region is exhausting and sometimes impossible because of poor tool accessibility. Therefore typically, the design of low overhang features is modified to dwindle the use of supports. The talk demonstrates the fabrication of a support-free closed impeller of 20.5 cm diameter processed at 30 µm and 60 µm layer thickness. A systematic investigation is conducted on the microstructure and mechanical properties characterization throughout the impeller including the critical regions tending to zero-degree overhang angle. The results will also present the evolution of the residual stress around the impeller.