Finite element simulation of thermal behavior in single-track multiple-layers thin wall without-support during selective laser melting

Abstract

The huge instantaneous energy is inputted in the powder layer during selective laser melting (SLM), which results in the transient high temperature and the complex temperature distribution. The temperature distribution and cooling rate of molten pool determine the microstructure after solidification, which affects the final performance. And the molten pool dimensions affect the final dimensional accuracy and performance. In this study, the temperature distribution, cooling rate and molten pool dimensions of the single-track multi-layer thin wall without-support during SLM is studied by the three-dimensional finite element model. Density is the main property of the powder layer which has the significant effect on the temperature field. A nonlinear transient finite element model is established by ANSYS parametric design language (APDL). The results of the simulation show that the maximum temperature, heat affect zone (HAZ) and molten pool dimensions increase as the number of layer increases, while the cooling rate decreases as the number of layer increases except for the first layer. The maximum temperature, HAZ and molten pool dimensions increase as the density of the powder layer decreases, and the cooling rate decreases as the density decreases. The conclusions are compared with those of the thin wall with-support in the published articles. Through considering the appearances of the thin walls without-support made by SLM and the cooling rates at the three different powder layer densities, the powder layer density with 60% is the best choice.