Spattering and oxidation phenomena during recycling of low alloy steel powder in laser powder bed fusion

March 10, 2021

Tatiana Fedina (1), Jesper Sundqvist (1), Alexander F.H. Kaplan (1)
Materials Today Communications, 27, March 2021. DOI: 10.1016/j.mtcomm.2021.102241


Low alloy steel; Spattering; Powder degradation; Recycling; Laser powder bed fusion; Additive manufacturing


This study reports on the impact of repeated powder recycling on the degradation of low alloy steel powder in Laser Powder Bed Fusion. The average powder particle size increased slightly upon recycling due to powder agglomeration and the presence of spatters and other ejecta from the process zone. The oxygen content showed a continuous growth after each recycle, while the other chemical elements of the recycled powder remained largely unchanged. A map of ejecta classification is presented, featuring various ejecta types formed during laser processing. Ejecta of increased diameter and different shapes were observed in the recycled powder, using high-speed imaging and Scanning Electron Microscopy. The ejecta were collected after each powder recycle to enable the calculation of the ejecta mass generated during the process. The result showed a direct correlation between oxygen content in the powder and spatter/ejecta formation with the number of recycling events. It is likely that the increase in oxygen contributes to powder spattering.

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Author Affiliation

(1) Luleå University of Technology, Department of Engineering Sciences and Mathematics, 971 87, Luleå, Sweden.