Laser powder bed fusion of 316L stainless steel with 2 wt.% nanosized SiO2 additives: powder processing and consolidation

Stylianou, Rafael, Evangelou, Angelos, Loizou, Alexandros, Kim, Donghyuk, Wharton, Julian, Koutsokeras, Loukas, Constantinides, Georgios, Delimitis, Andreas and Kyratsi, Theodora (2023) Laser powder bed fusion of 316L stainless steel with 2 wt.% nanosized SiO2 additives: powder processing and consolidation. Powder Technology, 427, [118714]. (doi:10.1016/j.powtec.2023.118714).

Abstract

Gas atomized 316L stainless steel powder was processed with 2 wt.% of nanosized SiO2 in a planetary ball milling (BM) system to produce feedstock material for laser powder bed fusion (L-PBF). X-ray diffraction (XRD) of powders revealed the development of micro-strains over increasing milling durations and the strain-induced ferrite formation. BM was limited in duration to preserve the austenitic phase and morphological characteristics analyzed by electron microscopy. In turn, 316L-2wt.% SiO2 feedstock powder was consolidated by L-PBF with varied process parameters and scanning strategies, that demonstrated a maximum density of 7.84 g/cm3 and relatively stable microhardness values close to 220 HV. A distinct (110) preferred orientation was observed in XRD pole figures of austenite for deeper melt pools over the building direction, whereas in-plane alignment reflected variations in scanning strategy. Furthermore, electron backscatter diffraction revealed columnar grains accompanied by the suspected depletion of SiO2, while electrochemical behavior displayed consistent characteristics.

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Contributors

Author: Julian Wharton

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