Layerwise scanning strategy combining Multiple beam shapes to enhance isotropy in high-power laser-based powder bed fusion of IN718

Beam shaping technology has transformed laser-based powder bed fusion of metals (PBF-LB/M), enabled increased productivity and expanded process window through the use of higher laser power, faster scanning speeds, and wider hatch distances. Unlike the state-of-the-art Gaussian laser profile, beam-shaped laser profiles with diameters typically greater than 100 μm and higher power levels tend to produce broader and flatter melt pools. This promotes epitaxial grain growth in alloys like Inconel 718, leading to large columnar grains and significant anisotropy in microstructural and mechanical properties. While such grains enhance high-temperature creep resistance, they adversely affect fatigue performance, tensile strength, and isotropy, which are critical for many applications. This article presents a novel approach, named as “beam switching”, combining layerwise exposure with ring-shaped and Gaussian beam profiles to balance productivity and isotropy in as-built parts. With a maximum build rate of 16 mm 3 /s, four times higher than state of the art (4.2 mm 3 /s), this method achieves isotropic microstructural properties (texture index represented by J-index of below 2) without compromising productivity. Detailed microstructural analysis reveals fine, circular grains similar to those produced by state-of-the-art process parameters, resulting in substantial improvements in as-built tensile properties, including ultimate tensile strength and yield strength. This approach further expands the process window by introducing the so-called "healing effect", which transforms previously non-viable process parameters into buildable conditions.