Mitigating Heat Accumulation Induced by Scan-Vector Shortening in Laser Powder Bed Fusion of Sharp-Edged Inconel 718 via Geometry-Informed Active Energy Modulation

Laser powder bed fusion (LPBF) enables the fabrication of geometrically complex metallic components, but sharp-edged features remain susceptible to localized heat accumulation because bidirectional meander scanning produces progressively shortened scanning vectors near acute apices. The resulting imbalance between repeated energy input and limited heat dissipation destabilizes melt-pool behavior and degrades surface integrity, densification and microstructural uniformity. In this study, a geometry-informed active energy modulation strategy was proposed for LPBF of Inconel 718 sharp-edged components. A dimensionless Power Reduction Factor (PRF) was formulated to couple laser power attenuation with scan-vector shortening. Coupled DEM–CFD simulations showed that power reduction in heat-accumulation-prone regions decreased peak temperature and suppressed excessive melt-pool expansion caused by adjacent-track thermal history. In situ coaxial photodiode monitoring revealed that apical heat accumulation intensified with i build height under insufficient power reduction, whereas increasing the PRF reduced the overheated zone. Among the tested conditions, PRF = 0.3 provided the most favorable balance between overheating and energy deficiency, minimizing apical surface roughness and maintaining a relatively uniform microhardness distribution above 290 HV0.1. Lower PRF values resulted in swelling and hardness degradation, while higher PRF values promoted track instability and lack-of-fusion defects. Microstructural characterization revealed a persistent intra-track hierarchy in a cellular dendritic scale, while location-dependent PDAS variations along the sharp-edged region were comparatively modest. The observed trends indicate that spatially graded power attenuation modifies local cellular-scale heterogeneity. These results demonstrate that PRF-based modulation provides a quantitative route for mitigating scan-vector-shortening-induced heat accumulation in sharp-edged geometries without additional cooling delays.