Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti-6Al-4V

A finite element model of Laser Powder Bed Fusion (LPBF) process applied to metallic alloys at a mesoscopic scale is presented. This Level-Set model allows to follow melt pool evolution and track development during building. A volume heat source model is used for laser/powder interaction considering the material absorption coefficients, while a surface heat source is used to consider the high laser energy absorption by dense metal alloys. An energy solver is applied considering convection and conductivity evolution in the system. Shrinkage during consolidation from powder to dense material is modelled by a compressible Newtonian constitutive law. An automatic remeshing strategy is also used to provide a good compromise between accuracy and computing time. Different cases are investigated to demonstrate the influence of the vaporisation phenomena, of material properties and of laser scan strategy on bead morphology.