The Study of Scan Speed and Laser Power Effects on the Molten Pool in Selective Laser Melting of Ti6Al4V Based on the Molten Motion Equations

Selective laser melting (SLM) is a laser powder-bed fusion method that offers great potentials in producing components with complex shapes and geometries. Process parameters like laser power and scan speed have significant effect on the induced temperature gradient which determines the molten pool dimensions and surface integrity. Due to the transient feature and fine dimensions of the molten pool, monitoring and measuring the induced temperature gradient and the pool dimensions are extremely challenging. In this article, a finite element model has been used to analyze the process and investigate the scanning speed and laser power parameters during the SLM process on a substrate of Ti6Al4V alloy. In this study, first the theoretical equations of laser have been investigated and after modeling, the accuracy of the modeled laser has been compared with the experimental model. After verifying the laser modeling, the FEM analysis of SLM has been carried out for various laser powers and scan speeds to study the effects of the mentioned process parameters. For the modelling, various physics assumptions have been simultaneously used in the software including heat transfer, solid to liquid phase changes equations, surface tension (Marangoni effect), and laminar fluid flow (Navier-Stokes equation) along with the gravity effect. Molten pool dimensions, temperature gradient along the laser moving heat source, width, and depth of the molten pool, as well as the occurrence of the balling effect phenomenon, have been studied separately in each case. The results obtained by FEM analysis have been compared with the experimental model, showing good compatibility.