Simulation and analysis of LPBF multi-layer single-track forming process under different particle size distributions

Abstract

Laser powder bed fusion (LPBF) has the advantages of rapid and customized production and has gradually been used in aerospace, biomedicine, and other fields. However, the current LPBF technology still faces many obstacles, such as the failure to fully explore the influence of the powder layer parameters (particle size distribution, thickness of spreading layer, etc.) on the LPBF multi-layer forming process. Based on the open-source discrete element method framework Yade and the open-source finite volume method framework OpenFOAM, the simulation flow for the LPBF multi-layer single-track process was established. Among them, the considered force influence factors included gasification recoil, surface tension, Marangoni effect, viscous force, mushy zone drag force, and gravity, and the considered thermal influence factors included gasification, convection, and radiation heat dissipation. In order to analyze the influence of particle size distribution and spreading layer thickness on the LPBF multi-layer process, the forming processes of the first eight layers of powder bed with three different particle size distributions and two different spreading layer thicknesses were calculated. Regarding the surface roughness of the formed layer, it was found that when the proportion of large-size particles increased, the surface roughness of the formed layer would increase. Regarding the actual thickness of the powder layer and the depth of the solidified track, it was found that they were mainly related to the thickness of the spreading layer, but were not affected by the particle size distribution. Regarding the porosity of the formed zone, it was found that when the spreading layer thickness was smaller, the higher the proportion of small-size particles, the lower the porosity of the formed zone; when the spreading layer thickness was larger, the smaller the proportion of large-size particles, the lower the porosity of the formed zone. This paper is expected to provide support for in-depth understanding of the effects of particle size distribution and spreading layer thickness on the LPBF multi-layer forming process.