Spattering and oxidation phenomena during recycling of low alloy steel powder in Laser Powder Bed Fusion

• 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.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

Nyckelord

Low alloy steel

Spattering

Powder degradation

Recycling

Laser Powder Bed Fusion

Additive manufacturing

Produktionsutveckling

Manufacturing Systems Engineering

Publikations- och innehållstyp

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