Numerical study of the AlSi10Mg selective laser melting process using a coupled DEM-FEM approach

Purpose This study aims to develop a high-fidelity discrete element method–finite element method (DEM-FEM) model for the laser powder bed fusion process, successfully enabling the fabrication of AlSi10Mg samples with outstanding mechanical properties. Design/methodology/approach The study first establishes a fully three-dimensional, coupled DEM-FEM model. Through the application of laser powder bed fusion remelting technology, the effects of laser power (400 W), remelting power (284 W) and scanning velocity (1.2 to 1.8 m/s) on the defect formation and macroscopic morphology of single-track AlSi10Mg melt pools are systematically simulated and analyzed. To validate the model, the densities of AlSi10Mg specimens produced by laser powder bed fusion and laser powder bed fusion remelting at various scanning speeds were experimentally measured. Subsequently, using optimized process parameters, the microstructures and mechanical properties of laser powder bed fusion and laser powder bed fusion remelting samples were comparatively evaluated. Findings The results demonstrate that the developed model can reliably predict both melt pool morphology and porosity evolution. Extremely high or low scanning velocities invariably induce porosity within the melt pool, whereas the porosity of remelted samples is substantially reduced. Remelted specimens exhibit an evident increase in the number of equiaxed grains and cellular substructures, resulting in enhanced mechanical performance. Moreover, the fracture mechanism of remelted samples shifts from brittle fracture to ductile fracture. Originality/value In summary, a DEM-FEM model capable of accurately predicting pore formation and melt pool geometry in the laser powder bed fusion process has been established. The influences of scanning speed and remelting on melt pool morphology and defect evolution are discussed in detail. Finally, the mechanisms underpinning the microstructural and mechanical modifications induced by remelting are elucidated.