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Various defects are produced during laser powder bed fusion (L-PBF) process, and can affect the quality of the fabricated part. Past studies have revealed that the defects formed are correlated with molten pool dimensions. Powder particles are thinly spread on a substrate during L-PBF process; hence, powder packing properties should influence the molten pool dimensions. This study has evaluated influence of particle size on powder packing properties and molten pool dimension obtained from numerical simulation. Using particles with different average diameter (Dav) of 24, 28, 32, 36, and 40 $\mu$m, a series of discrete-element method (DEM) simulations were performed. Packing fraction obtained from DEM simulations became high as Dav became small. Several particles could piled up for small Dav, whereas particles spread with almost one-particle diameter thickness for large Dav. Moreover, packing structure was inhomogeneous and sparse for large Dav. Then we performed multiphysics computational fluid dynamics (CFD) simulations incorporating particles' position as initial solid metal volume. Molten pool width obtained from the simulations was hardly dependent on the Dav and was roughly equivalent to the laser diameter used in the simulations. In contrast, molten pool depth became small as Dav became small. The results suggest that importance of specific surface area, that is, the powder bed with smaller Dav can absorb larger thermal energy because of the larger specific surface area due to the large powder bed thickness and piling up multiple particles.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: laser powder bed fusion, particle size, powder spreading, discrete-element method, packing fraction, packing homogeneity, multiphysics CFD simulation

刊行年月日: 2024-04-01

出版者: MDPI AG

掲載誌:

• Journal of Manufacturing and Materials Processing (ISSN: 25044494) vol. 8 issue. 2 71

研究助成金:

• Innovative Science and Technology Initiative for Security JPJ004596

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.3390/jmmp8020071

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更新時刻: 2024-04-05 12:30:21 +0900

MDRでの公開時刻: 2024-04-05 12:30:21 +0900