A Multiphase CFD Model for the Prediction of Particulate Accumulation in a Laser Powder Bed Fusion Process

Laser Powder Bed Fusion (L-PBF) is a powder based subcategory of metal additive manufacturing. In L-PBF systems an inert gas flow is used to avoid oxidation of the metal alloy powder and components but is also used to remove unwanted by-products produced from the vaporisation of material. By-products produced during in L-PBF can cause attenuation of the laser and re-deposition of unwanted by-products over the processing area which can affect the mechanical properties of as built components. The two main by-products produced in L-PBF are spatter caused from melt pool instabilities and recoil pressure from the metal vapour plume, and particulate condensates. A multiphase computational fluid dynamics model developed in ANSYS Fluent simulates the argon gas flow in a Renishaw AM250 machine validated using hotwire anemometry testing. This model is then coupled with a spatter expulsion discrete phase model supported by high speed imaging analysis and a tertiary phase model for a representative expulsion of particulate condensates is developed.