The effect of powder characteristics on build quality of high purity tungsten produced via Laser Powder Bed Fusion (LPBF)

The effect of powder characteristics on build quality of high purity tungsten produced via Laser Powder Bed Fusion (LPBF)

The effect of powder characteristics on build quality of high purity tungsten produced via Laser Powder Bed Fusion (LPBF) 150 150 UKAEA Opendata
UKAEA-CCFE-PR(19)29

The effect of powder characteristics on build quality of high purity tungsten produced via Laser Powder Bed Fusion (LPBF)

Two high purity tungsten powders, produced via different manufacturing techniques, were characterized to determine size distribution, morphology, thermal properties and flow characteristics and thus, the likely suitability for Laser Powder Bed Fusion (LPBF) production. Specimens from duplicate builds were produced with the two powders and characterized for density, defect mechanisms and thermal penetration into the substrate plate to compare apparent power densities. The first powder was a chemically reduced powder with irregular morphology and the second, a plasma spheroidized powder with highly spherical morphology. The latter was found to have tighter morphological control and size distribution, having a third of particles at the modal particle size in comparison to a fifth of the reduced powder. This led to better flow characteristics, and an increase of 1.5 gcm-3 (1500 kg m-3) in the packing densities seen in the powder bed which corresponds to 57 % theoretical density versus 50 % theoretical density in the chemically reduced powder. As a result, the specimens produced from the plasma spheroidized powder had higher densities (97.3 % vs. 88.5 %) and the dominant defect mechanism moved from lack of fusion dominated in the chemically reduced powder to cracking dominated in the plasma spheroidized. The plasma spheroidized powder also showed higher apparent power densities as evidenced by an 80 % deeper penetration of the laser into the substrate plate.

Collection:
Journals
Journal:
Metallurgical and Materials Transactions A
Publisher:
Springer
Published date:
01/01/2020