2026/01/05
Support-free fabrication of IN625 low-angle overhang structures using laser powder bed fusion (LPBF)
Kumar, A.; Attarian Shandiz, M.; Kumar, M.; Jena, A.; Brochu, M. (2025). Support-free fabrication of IN625 low-angle overhang structures using laser powder bed fusion (LPBF). Materials & Design, vol. 259, 2025, 114873.
Support-free IN625 overhang bars (60 × 10 × 7 mm3) were successfully fabricated using laser powder bed fusion (LPBF), achieving a minimum overhang angle of 5° at 30 µm layer thickness and 10° at 60 µm layer thickness. Supported bars were also fabricated to conduct a systematic comparison. Residual stress analysis revealed an increase in residual stresses with decreasing overhang angles. The downskin surface topography exhibited pronounced stair-stepping effects and powder adhesion, especially at low angles. Microstructural characterization confirmed columnar grains spread through the bulk region and small equiaxed grains in the downskin region of the low-overhang angle bars. While the primary dendrite arm spacing remained consistent within the bulk, it increased in the downskin region due to reduced heat dissipation. Correspondingly, the micro-hardness remains consistent in the bulk region, it decreases in the downskin region for the overhang angles below 30°. Uniaxial-tensile tests demonstrate consistent strength, while elongation is higher for increased overhang angle.