Page 133 - MSAM-2-3

Materials Science in Additive Manufacturing Powder alteration caused by L-PBF process

Figure 19. Particle-size distribution of lattices parts with different cell Figure 21. D-values of new powder versus powder reused 12 times.
sizes (fourth replicate for each cell size).

Figure 22. Particle-size distribution of new powder versus powder reused
Figure 20. D-values of lattices depending on cell sizes. 12 times.

values of powder reused 12 times. Significant increases ratio of printed components in these lattice cylinders
could be observed in D90, D50, and D10, of 21.7%, changes the PSD of the powder trapped in the lattice
16.6%, and 15.5%, respectively. The PSD moved larger structure. This outcome might be caused by a variety of
particles rightward, followed by a slight drop in fine circumstances. The balling defect might be responsible
particles and a relevant increase in the proportion of large for the increase in powder diameter to 500 µm due to
particles (Figure 22). This result has also been reported the creation of partially melted particles . Furthermore,
[5]
by many researchers studying the effects of reuse cycles formation of spatters could be the primary reason for the
on powder size characteristics [10,11,25,34,36,38-41] . For example, increase in PSD. Soundarapandiyan et al. [11,42] and Sutton
Soundarapandiyan et al. and Richard and O’Leary et al. et al. observed that powder near the melt pool was
[22]
[11]
[10]
observed the same behavior of the Ti-6Al-4V powder PSD,
which shifted rightward after five reuse cycles. In another coarser due to the presence of spatters, partially melted
study, we confirmed the similar PSD behavior after reusing particles, hard sintering, and agglomerations.
maraging steel powder 8 times . A small proportion of large particles in the diameter
[36]
Figure 20 shows that D-values D10 and D50 increased range of 200–1000 µm (Figures 5, 8, 12, 14, and 22) were
by 16.2% and 9%, respectively, while the D90 decreased by likely aggregates in the PSDs samples analyzed by the
13% when the area ratio was increased from 2.4 to 8.4. As a Mastersizer 3000, since particles in this size range were not
result, we can deduce that increasing the area and volume observed using the electron microscope.

Volume 2 Issue 3 (2023) 10 https://doi.org/10.36922/msam.1781