Finite element modeling of thermal behavior in selective laser melting

Abstract

Selective Laser Melting (SLM) is an important additive manufacturing method with widespread applications in aerospace, dental and tool making industry. SLM creates products layer by layer, so the heat accumulation phenomenon occurs during the process of SLM. Meanwhile, the effective heat conductivity coefficient varies with the thickness and the temperature of the powder bed. The variation of heat conductivity coefficient results in mutative thermal distribution on different layers. Finite element method (FEM) was used to simulate the thermal distribution during the process of fabricating a small brick by selective laser melting AlSilOMg powders. The finite element model was constructed by COMSOL Multiphysics. The results showed that there are differences between the size of molten pool, the maximum temperature and the recovery time across different layers during the process of SLM, which can be explained by the heat accumulation phenomenon and the varied effective heat conductivity coefficient. The heat accumulation and decreased heat dissipation by conduction leads to the increase in the length of the molten pool, by 15.49%, 10.27%, 8.89%, 6.11%, 1.99% and 0.51% respectively, from the first layer to the sixth layer. The maximum temperature increases gradually from 1730.69 °C in the first layer to 1864 °C in the sixth layer. Furthermore, the phenomenon of remelting was observed in this research.