A new ray tracing heat source model for mesoscale CFD simulation of selective laser melting (SLM)

•New heat source considering laser-matter interactions in SLM was developed.•Heat absorption was determined through reasonable ray tracing physical models.•Numerical simulation results of SLM showed a good agreement with experiments.•Influence of laser power on absorption was revealed through simulations. The present work was aimed to develop a new ray tracing heat source model used in mesoscale finite volume method (FVM) simulations for the selective laser melting (SLM) process. By means of the metal-gas interface built via the volume of fluid (VOF) method, the developed model simulated the interactions between the laser beam and the powder bed. Multiple reflections of the laser beam at the surface of the metal powders were taken into account in the modeling. Integrated into the commercial software, FLOW3D, the heat source model was validated by the comparison between the calculation results and previous experiments. 3-D mesoscale simulations for the SLM process of 316 L stainless steel were performed. The result indicated that the proposed ray tracing heat source model was able to model the laser heating process of the SLM. Better than the conventional one, the new heat source model identified the local defects during the SLM process, such as the balling behavior.