Metal Additive Manufacturing Conference - MAMC 2020

Moisture can potentially affect any production process that use metal powder, both the processing itself and the material that is produced. Here we study laser powder bed fusion (L-PBF) and the effect of moisture on built nickel-base material. We also present research on how humidity, and in turn moisture content, can affect processability including spreadability. In the first part, one lot of nickel-base powder was split into two equal batches. One batch was moisturized using a C1000-40 climate chamber, the other was untreated. We built bars with both batches for mechanical testing in an EOS M100 with a cold build plate. The moisture content of the two powder batches, before and after the build-jobs, were determined using Karl Fischer (KF) titration. Moisturization resulted in a content of 56 µg/g while the untreated powder contained 29 µg/g. These levels were only slightly reduced during the 14 h build jobs. This is notable, and means that the built material should reflect any impact that the moisture has. Still, the impact toughness was only marginally affect while the O and H content of the built material increased significantly. In the second part, we present research on how spreadability can be evaluated with commercially existing devices and how humidity can affect spreadability.