A nonequilibrium thermal model for direct metal laser sintering

A three-dimensional numerical model based on nonequilibrium thermal effect for direct metal laser sintering (DMLS) with a moving laser beam is developed. The effects of surface tension, buoyancy force, and permeability as well as volume shrinkage are taken into account. The nonequilibrium model is discretized by the finite volume method and solved numerically using the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm with power-law scheme in staggered mesh. The surface temperature distribution and shapes of top surface and liquid-mushy and mushy-solid interfaces are investigated. The results show that mushy zone and heat-affected zone are formed during DMLS, and the melting pool size is dominated mainly by surface tension and buoyancy force. The parametric study shows that the top surface and liquid-mushy and mushy-solid interfaces become lower with increasing laser intensity, increasing initial porosity, or decreasing scanning velocity.