| Abstract Scope |
The molten pool flow, particularly the keyhole effect, in the selective laser melting process, plays a key role in the defects which are difficult to be observed through experiments. In this study, we derived a new formulation of evaporation for metal alloys from thermodynamics considering the chemical compositions, and the formation of the keyhole was simulated using the Finite Volume Method (FVM) with the Volume of Fraction method to track the gas-liquid interface, where the multi-reflection of the laser within the keyhole and powder bed was incorporated using a ray-tracing algorithm. The geometry features of the simulated keyhole and melting pool showed a good agreement with the experimental observation by ultrahigh-speed X-ray imaging in Argonne National Lab. To understand the physical mechanisms of keyhole, the laser energy distribution on the keyhole surface, and the driving forces (e.g. Marangoni force, recoil pressure) on the keyhole surface were further analyzed |