Influence of substrate surface morphology on powder spreading in laser powder bed fusion process

Abstract

Controlling the quality of the powder bed is critical for guaranteeing component quality in laser powder bed fusion (LPBF). In this work, the discrete element method is used to examine how substrate surface morphology, including the roughness and texture angle, affects powder bed quality. The results indicate that the bed quality is more sensitive to changes in surface roughness than texture angle. Powder coverage can be improved by increasing the texture angle. The force analysis reveals that on rough surfaces, the contact force acting on the substrate has strong fluctuations. The particle-substrate contact force under the piles has an increasing-decreasing trend with the distance from the scraper increasing. In addition, the in-situ re-coating technique at a proper gap increment can effectively fill the depressions generated from the rough surface, achieving more uniform and dense powder beds. The findings provide a theoretical basis for optimizing powder-spreading strategies in LPBF process.