An analytical model of the melt pool and single track in coaxial laser direct metal deposition (LDMD) additive manufacturing

Abstract

An analytical model was developed for the melt pool and single scan track geometry as a function of process parameters. For computational efficiency, the developed model has simple mathematical forms with essential physics taken into account, without the need for complicated numerical simulation. In this research, a non-diverging Gaussian laser beam and coaxial diverging Gaussian powder stream combination is used to represent the coaxial laser direct metal deposition (LDMD) process. Analytical laser-powder interaction model is used to obtain the distribution of attenuated laser intensity and temperature of heated powders at the substrate. On the substrate, the melt pool is calculated by integrating Rosenthal's point heat source model. An iterative procedure is used to ensure the mass–energy balances and to calculate the melt pool and catchment efficiency. By assuming that the assimilated powder will reshape due to surface tension before solidification, a simple clad geometry model is established. The proposed model is used to simulate the geometry of single track depositions of Ti6Al4V, which shows a good agreement between model prediction and experimental results. This work demonstrates that the developed model has the potential to be used to narrow the parameter space for process optimization.