Journal
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Volume 210, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijmecsci.2021.106740
Keywords
Directed energy deposition; Additive manufacturing; Powder particle; Defocused amount; Gas flow rate; Nozzle diameter
Categories
Funding
- Liaoning Provincial Natural Science Foundation [2019-KF-05-07]
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The study found that in the DED-AM process, a negative defocused amount benefits the flight path of powder particles, allowing higher laser energy to be applied to the deposition layer. Increasing both the carrier gas and shield gas flow rates can accelerate powder particle speeds, leading to a reduction in laser energy attenuation and average temperature rise.
The spatial distribution of the flying powder particles was simulated by the established integrated model, in which computational fluid dynamics and discrete element methods were combined. In addition to the finite element model of heat transfer, the influences of the defocused amount, gas flow rate, and nozzle diameter on the DED-AM process were studied. Comparison with experimental observations can validate the proposed models. The results indicate that the negative defocused amount is benefit for powder particles to fly on the melt pool center and higher laser energy can be applied to the deposition layer. The powder particle speeds can be accelerated by increasing both the carrier gas and shield gas flow rates. As a result, the laser energy attenuation and the average temperature rise of powder particles decrease. However, the shield gas can lead to scattering of the powders, which causes the higher average temperature rise. When the carrier gas velocity remains constant, an excessively high or low nozzle diameter can lead to an increase in the divergence angle. The divergence angle can be minimized by the optimal selection of nozzle diameter.
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