Elucidating the impact of severe oxidation on the powder properties and laser melting behaviors

[Display omitted] •A correlation among the powder characteristics, recoating process and laser melting behavior was established.•The influence of severe surface oxidation on the microstructure and mechanical performance of L-PBF builds was examined.•A novel ceramic layer-coated 316L SS alloy with un...

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Bibliographic Details
Published in:	Materials & design Vol. 221; p. 110959
Main Authors:	Zhou, Weiwei, Takase, Nina, Dong, Mingqi, Watanabe, Naoki, Guo, Suxia, Zhou, Zhenxing, Nomura, Naoyuki
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 01-09-2022 Elsevier
Subjects:	Laser powder bed fusion Microstructures Oxidation Powder flowability Stainless steel Laser powder bed fusion Powder flowability Oxidation Microstructures Stainless steel
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Summary:	[Display omitted] •A correlation among the powder characteristics, recoating process and laser melting behavior was established.•The influence of severe surface oxidation on the microstructure and mechanical performance of L-PBF builds was examined.•A novel ceramic layer-coated 316L SS alloy with uniform oxide dispersions was in situ synthesized.•Advanced metallic parts could be developed by the positive utilization of powder oxidation and the L-PBF process. In this work, commercial 316L stainless steel (SS) powder was used to experimentally determine the impacts of severe oxidation on the powder characteristics and laser powder bed fusion (L-PBF) melting behaviors. The morphology, surface state, and laser absorptivity of both virgin and oxidized powders were systematically characterized. Their impacts on the flowability and powder bed quality were monitored by custom-designed recoating experiments and powder shear tests. The results of an in situ wetting analysis and microstructure evaluation were compared to establish a correlation between the powder characteristics and laser fusion. The powder oxidation enhanced L-PBF processability by improving the homogeneity of powder spreading and the formation of stable, consecutive laser beads. A thin ceramic layer-coated SS alloy reinforced with uniform (Si, Mn)-based oxides was synthesized by the L-PBF processing of severely oxidized powders. The mechanical strength of this alloy was found to be similar to that processed using the virgin powders, whereas the elongation was slightly decreased, likely due to the amorphous oxide feature and the mechanical oxide-Fe interface. This study provides a systematic understanding of powder reuse and new insight into the potential for economically developing high-performance parts by the positive utilization of powder oxidation and the L-PBF process.
ISSN:	0264-1275 1873-4197
DOI:	10.1016/j.matdes.2022.110959