A new model framework of laser powder bed fusion by integrating a powder-scale model with a thermodynamic database

• A CFD-DEM-VOF model coupled with a thermodynamic database was developed. • The effects of laser power, track number, and hatch distance on the LPBF were studied. • Powders’ random configuration causes the asymmetrical temperature distribution. • A laser beam with a lower power density leads to pore defects in the laser track. • Multi-track LPBF improves surface quality and eliminates possible discontinuity. Laser powder bed fusion (LPBF) has been increasingly practised in powder-based additive manufacturing industries, yet the fundamentals including multiphase flow and phase change were not well understood. This work develops a powder-scale computational fluid dynamics-discrete element method-volume of fluid (CFD-DEM-VOF) model integrated with a temperature-dependent thermodynamic database to simulate the multiphase flow with phase change in the LPBF process. The integrated model is validated by comparing prediction results with the experimental measurements. Several LPBF cases with different laser powers, track numbers, and hatch distances are numerically studied. The simulation results demonstrate that the model can capture the key phenomena and key features in the LPBF process observed experimentally, including temperature distribution and morphology of molten tracks. The results also show the random configuration of the powders leads to the asymmetrical distribution of the temperature in the molten pool. The laser beam with a lower power density causes pore defects in the transition zone of the laser track because of partially melted particles, causing a rough molten surface. Incorporating an overlap between two molten tracks is crucial for enhancing the surface quality and mitigating issues such as discontinuity and particle adherence along the track edge. This model provides a cost-effective solution for comprehending and optimizing multiphase flow and phase change phenomena within the LPBF process in additive manufacturing.