Volumetric heat source model for laser-based powder bed fusion process in additive manufacturing

Abstract

Laser-based powder bed fusion (L-PBF) is one of the most widely used additive manufacturing methods. Its most striking feature is the melt pool in the powder bed, which is formed by a laser heat source. Many physical phenomena occur as a result of the interaction of the heat source with metal powders. Spattering, melting and sintering to each other of the metal powders (phase and shape change), liquid metal movement induced by buoyancy force and surface tension gradient, high evaporation and resulting recoil pressure, fluctuations and deteriorations on the liquid metal surface, plume type structures can be given as examples. The most important point in terms of L-PBF and similar methods is to predict the melt pool dimensions and temperature distribution in the powder bed. However, the phenomena mentioned above complicate the process considerably and require high calculation costs. Volumetric heat sources are a frequently used prescription in terms of simplifying the modeling of the process and reducing the calculation cost. However, such heat source models may contain many non-standard parameters and do not always produce reasonable results. In this study, a dynamic heat source model is presented for use in powder bed systems. Some discussions related to the problems such as uncertainties in absorptivity ratios used in L-PBF are also presented.