An analytical model for hatch-wise thermal histories near overhangs in laser powder bed fusion

Abstract Overhanging features in laser powder bed fusion (LPBF) are prone to heat accumulation and related defects because of limited heat dissipation. We propose a reduced analytical thermal model for efficient prediction of hatch-wise temperature histories near overhanging boundaries. The model focuses on inter-hatch temperature and the onset of excessive heat accumulation. It uses the two-dimensional Green’s function for transient heat conduction and image sources to enforce adiabatic conditions at the top and slanted boundaries of an ideal wedge. A hatch sequence is represented by concentrated, instantaneous line-energy inputs at hatch centers, enabling rapid superposition-based computation of temperature histories for long sequences. Predictions are benchmarked against Finite Element (FE) simulations. Across multiple overhang angles and stripe widths and for 316 L and AlSi10Mg under different process conditions, the model closely reproduces inter-hatch temperature evolution and the characteristic overheating trend toward the overhanging edge. The results demonstrate the roles of distance to the edge, overhang angle, and return time in controlling the quasi-steady inter-hatch temperature and the near-edge burned zone, defined where the preheating temperature exceeds the solidus threshold. Burned-zone sizes measured from metallographic cross-sections of 24 overhanging 316 L specimens show trends consistent with the analytical predictions. The proposed framework provides a fast, physics-based tool for assessing overheating near overhangs and a basis for large parametric studies and surrogate models supporting hatch-wise parameter adaptation.