A study published in Powder Technology systematically evaluated the effects of particle size distribution, powder morphology, and ambient humidity on the Hall flowability of steel powder for additive manufacturing. Using gas-atomized 316L powder, the study found that aspect ratio is the primary factor determining flowability, that a higher D10 value can increase the probability and rate of flow, and that ambient humidity amplifies the powder's sensitivity to distribution width D90–D10. The study also established a quantitative regression model for optimizing powder morphology and particle size.