TY - JOUR
T1 - Impact of atomization gas on characteristics of austenitic stainless steel powder feedstocks for additive manufacturing
AU - Gao, M. Z.
AU - Ludwig, B.
AU - Palmer, T. A.
N1 - Funding Information:
The authors wish to thank the Applied Research Laboratory, Center for Innovative Sintered Products and Material Characterization Laboratory at Penn State for the use of their equipment, Dr. Ekaterina Bazilevskaya for the training on Malvern Morphologi G3SE system for particle characterization, Mr. Tim Stecko at the Energy and Environmental Sustainability Laboratories (EESL) at for his support with X-ray CT scans, the training on porosity analysis, and helpful discussions.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/5
Y1 - 2021/5
N2 - Given the complexity of the laser-material interactions prevalent in powder bed fusion additive manufacturing, the need for tight control of alloy composition in the metal powder feedstock is leading to the use of specific gases during atomization. These changes in atomization gas also impact powder flow and packing. In order to identify the magnitude of this impact, two nitrogen atomized and one argon atomized 316 L austenitic stainless steel powders with similar size distributions were characterized using traditional powder characterization tools and rotating drum and annular shear rheological tools. While the traditional characterization tools and particle size measurements did not differentiate between the powders, these rheological tools allowed connections between the particle morphologies and rheological properties and powder performance to be identified. In particular, the argon atomized powders displayed higher aspect ratios, which translate into more spherical morphologies, and improved flow, defined by lower avalanche angles, when tested in the rotating drum. On the other hand, these differences in flow properties were not captured in the corresponding basic flow and specific energy measurements made with the annular shear tools. Variations in the powder packing properties and internal powder porosity in the different powder lots decreased the powder mass and introduced increased uncertainty in the force and torque measurements. The void spacing between loosely packed powders was also measured and showed how changes in particle size distribution and morphology impacted both packing density and permeability. Larger void spacing produced higher permeability values, indicating greater gas flow through the loosely packed powder.
AB - Given the complexity of the laser-material interactions prevalent in powder bed fusion additive manufacturing, the need for tight control of alloy composition in the metal powder feedstock is leading to the use of specific gases during atomization. These changes in atomization gas also impact powder flow and packing. In order to identify the magnitude of this impact, two nitrogen atomized and one argon atomized 316 L austenitic stainless steel powders with similar size distributions were characterized using traditional powder characterization tools and rotating drum and annular shear rheological tools. While the traditional characterization tools and particle size measurements did not differentiate between the powders, these rheological tools allowed connections between the particle morphologies and rheological properties and powder performance to be identified. In particular, the argon atomized powders displayed higher aspect ratios, which translate into more spherical morphologies, and improved flow, defined by lower avalanche angles, when tested in the rotating drum. On the other hand, these differences in flow properties were not captured in the corresponding basic flow and specific energy measurements made with the annular shear tools. Variations in the powder packing properties and internal powder porosity in the different powder lots decreased the powder mass and introduced increased uncertainty in the force and torque measurements. The void spacing between loosely packed powders was also measured and showed how changes in particle size distribution and morphology impacted both packing density and permeability. Larger void spacing produced higher permeability values, indicating greater gas flow through the loosely packed powder.
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U2 - 10.1016/j.powtec.2020.12.005
DO - 10.1016/j.powtec.2020.12.005
M3 - Article
AN - SCOPUS:85100024940
SN - 0032-5910
VL - 383
SP - 30
EP - 42
JO - Powder Technology
JF - Powder Technology
ER -