Numerical analysis of powder bed generation and single track forming for selective laser melting of SS316L stainless steel

摘要

The discrete element method (DEM) and the finite volume method (FVM) were used to build a 3D numerical model to simulate the selective laser melting process (SLM). The Marangoni effect and the recoil pressure were incorporated in the model. Experiments for the single track were performed for verification. The numerical results indicated that melt tracks with different morphologies were formed when the same linear energy density (LED) was applied. The formation mechanism of the melt track defects including balling, porosity and distortion were analyzed. It was found that the balling defect was concluded to be resulted by insufficient energy input incapable of melting the substrate. The distortion defect originated from the combined effect of the random distribution of powder particles and the Marangoni effect. In the keyhole-mode laser melting process, the unsteady behavior of the molten pool and keyhole led to the porosity defect.