Marangoni and buoyancy effects on direct metal laser sintering with a moving laser beam

A three-dimensional model describing melting and resolidification of a direct metal laser sintering process under the irradiation of a moving Gaussian laser beam is developed. Effects of shrinkage and natural convection driven by the surface tension and buoyancy force are taken into account. The energy equation is formulated using a temperature-transforming model and solved by the finite-volume method. The temperature distribution and velocity field are investigated. The results show that increasing the initial porosity of the powder bed enlarges the depth of the melt-solid interface and that the laser intensity has great influence on both the depth and width of the liquid pool. The whole molten pool shifts toward the direction opposite the laser scanning as the scanning velocity increases.