Keywords and Phrases
Discrete Element Method; Flowability; Powder Characterization; Powder Recycling; Selective Laser Melting
"Powder-bed fusion refers to a subset of additive manufacturing (AM) methods which successively melts and solidifies selected regions within a powder bed on a layer-by-layer basis to construct components directly from computer-aided design files. Laser Powder-Bed Fusion (L-PBF) is a process among the powder-bed fusion techniques that utilizes a laser to consolidate particles into a material with little porosity. During the L-PBF process, the large energy input from the laser causes the production of ejecta in the form of laser spatter and condensate, both of which have the potential to settle in the surrounding powder bed compromising its reusability. In order to better understand the impact of ejecta on powder recyclability, samples of 304L laser spatter and condensate were characterized in terms of morphology, chemistry, and microstructure. Differences between ejecta and virgin powder were used as a basis for understanding the evolution in 304L powder properties with reuse in the L-PBF process over the course of 7 iterations, which revealed an improvement in flowability with recycling. The effects of evolving powder properties on the tensile and impact toughness properties were also assessed for capturing possible deterioration in mechanical performance. Due to the improvement in powder flowability during recycling, the effects of alterations in the particle size were further investigated using the Discrete Element Method (DEM). Through development of a mathematical definition of spreadability, differences in the particle size distribution as well as recoating velocity and layer thickness revealed changes in the powder-bed quality providing crucial knowledge of the mechanisms behind the powder spreading process"--Abstract, page iv.
Leu, M. C. (Ming-Chuan)
Newkirk, Joseph William
Liou, Frank W.
Bristow, Douglas A.
Mechanical and Aerospace Engineering
Ph. D. in Mechanical Engineering
Honeywell Federal Manufacturing and Techologies, LLC
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- Powder characterisation techniques and effects of powder characteristics on part properties in powder-bed fusion processes
- Characterization of laser spatter and condensate generated during the selective laser melting of 304L stainless steel powder
- Characterization of AISI 304L stainless steel powder recycled in laser powder-bed fusion
- Evolution of AISI 304L stainless steel part properties due to powder recycling in laser powder-bed fusion
- Modeling powder spreadability in laser-powder-bed fusion using the discrete element method
© 2020 Austin Taylor Sutton, All rights reserved.
Dissertation - Open Access
Electronic OCLC #
Sutton, Austin Taylor, "Characterization and recyclability of 304L stainless steel powder for use in the selective laser melting process" (2020). Doctoral Dissertations. 2876.