Correlation of Powder Degradation, Energy Absorption and Gas Pore Formation in Laser-Based Powder Bed Fusion Process of AlSi10Mg0.4

Gas pore formation observed during laser-based powder bed fusion is yet not fully understood. This study is a comprehensive investigation of the mechanisms of hydrogen pore formation in the powder bed fusion process of AlSi10Mg0.4 via laser beam. The influence of varying process parameters such as hatch distance, layer thickness and build plate temperature as well as the impact of virgin and long-term reused powder on part porosity and melt pool characteristics is investigated in detail. A novel, very efficient method to characterize powder aging by the correlation of powder gray value measurements with the oxygen content is presented. The relation between powder aging and the change of the absorption coefficient reveals the origin of gas formation as being intimately related to the energy input. Vacuum heat treatment of as-built parts indicates the potential of hydrogen removal in a postprocessing step with the prospect of welding additively manufactured aluminum parts.