Moisture in Metal Powder and Its Implication for Processability in L-PBF and Elsewhere

The impact of moisture on flowability and spread- ability is discussed. More notably we also present research on the impact of moisture on built nickel-base material. One lot of a newly opened Hastelloy X (HX) L-PBF powder was split into two equal batches. One batch was moisturized using a programmable climate chamber, the other was un- treated. We built bars with both batches for mechanical testing, in an EOS M100, with a cold build plate. The mois- ture content of the two powder batches, before and after the build-jobs, were determined using Karl Fischer titration (KF). Regarding the periodical monitoring of moisture con- tent, it is not needed according to the findings of this paper. More moisture contributes to a slightly higher O-content in the built material, and in turn, a very slight reduction in im- pact toughness. If a newly purchased powder exhibits poor flowability or high oxygen content, the analysis using oven- desorption followed by KF is recommended. If the moisture content is high, a drying of the powder is recommended