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Title: Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing

The results of detailed experiments and finite element modeling of metal micro-droplet motion associated with metal additive manufacturing (AM) processes are presented. Ultra high speed imaging of melt pool dynamics reveals that the dominant mechanism leading to micro-droplet ejection in a laser powder bed fusion AM is not from laser induced recoil pressure as is widely believed and found in laser welding processes, but rather from vapor driven entrainment of micro-particles by an ambient gas flow. The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results. Hydrodynamic drag analysis is used to augment the single phase flow model and explain the entrainment phenomenon for 316 L stainless steel and Ti-6Al-4V powder layers. The relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Materials Science Division, Physical and Life Sciences Directorate
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Laser Science and Systems Engineering, NIF and Photon Sciences Directorate
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Computational Engineering, Engineering Directorate
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Laser Systems Engineering Operations, Engineering Directorate
Publication Date:
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Fluid dynamics; Metals and alloys
OSTI Identifier:
1395471

Ly, Sonny, Rubenchik, Alexander M., Khairallah, Saad A., Guss, Gabe, and Matthews, Manyalibo J.. Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing. United States: N. p., Web. doi:10.1038/s41598-017-04237-z.
Ly, Sonny, Rubenchik, Alexander M., Khairallah, Saad A., Guss, Gabe, & Matthews, Manyalibo J.. Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing. United States. doi:10.1038/s41598-017-04237-z.
Ly, Sonny, Rubenchik, Alexander M., Khairallah, Saad A., Guss, Gabe, and Matthews, Manyalibo J.. 2017. "Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing". United States. doi:10.1038/s41598-017-04237-z. https://www.osti.gov/servlets/purl/1395471.
@article{osti_1395471,
title = {Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing},
author = {Ly, Sonny and Rubenchik, Alexander M. and Khairallah, Saad A. and Guss, Gabe and Matthews, Manyalibo J.},
abstractNote = {The results of detailed experiments and finite element modeling of metal micro-droplet motion associated with metal additive manufacturing (AM) processes are presented. Ultra high speed imaging of melt pool dynamics reveals that the dominant mechanism leading to micro-droplet ejection in a laser powder bed fusion AM is not from laser induced recoil pressure as is widely believed and found in laser welding processes, but rather from vapor driven entrainment of micro-particles by an ambient gas flow. The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results. Hydrodynamic drag analysis is used to augment the single phase flow model and explain the entrainment phenomenon for 316 L stainless steel and Ti-6Al-4V powder layers. The relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.},
doi = {10.1038/s41598-017-04237-z},
journal = {Scientific Reports},
number = 1,
volume = 7,
place = {United States},
year = {2017},
month = {6}
}