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Title: In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing

Abstract

Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s–1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onset of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case.more » It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1392171
Alternate Identifier(s):
OSTI ID: 1420283
Report Number(s):
LLNL-JRNL-740801
Journal ID: ISSN 2352-9407; S2352940717302123; PII: S2352940717302123
Grant/Contract Number:  
15-ERD-037; AC52-07NA27344
Resource Type:
Journal Article: Published Article
Journal Name:
Applied Materials Today
Additional Journal Information:
Journal Name: Applied Materials Today Journal Volume: 9 Journal Issue: C; Journal ID: ISSN 2352-9407
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 47 OTHER INSTRUMENTATION; Additive manufacturing; 3D printing; Selective laser melting; Powder bed fusion; Optical absorption; Laser keyhole; Metal powder; Metal liquid absorptivity

Citation Formats

Trapp, Johannes, Rubenchik, Alexander M., Guss, Gabe, and Matthews, Manyalibo J. In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing. Netherlands: N. p., 2017. Web. doi:10.1016/j.apmt.2017.08.006.
Trapp, Johannes, Rubenchik, Alexander M., Guss, Gabe, & Matthews, Manyalibo J. In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing. Netherlands. https://doi.org/10.1016/j.apmt.2017.08.006
Trapp, Johannes, Rubenchik, Alexander M., Guss, Gabe, and Matthews, Manyalibo J. 2017. "In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing". Netherlands. https://doi.org/10.1016/j.apmt.2017.08.006.
@article{osti_1392171,
title = {In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing},
author = {Trapp, Johannes and Rubenchik, Alexander M. and Guss, Gabe and Matthews, Manyalibo J.},
abstractNote = {Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s–1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onset of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case. It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.},
doi = {10.1016/j.apmt.2017.08.006},
url = {https://www.osti.gov/biblio/1392171}, journal = {Applied Materials Today},
issn = {2352-9407},
number = C,
volume = 9,
place = {Netherlands},
year = {Fri Dec 01 00:00:00 EST 2017},
month = {Fri Dec 01 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1016/j.apmt.2017.08.006

Citation Metrics:
Cited by: 231 works
Citation information provided by
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Works referencing / citing this record:

In-plane anisotropy of selective laser-melted stainless steel: The importance of the rotation angle increment and the limitation window
journal, January 2018

  • Hitzler, Leonhard; Hirsch, Johann; Tomas, Josef
  • Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, Vol. 233, Issue 7
  • https://doi.org/10.1177/1464420718757068

In-plane anisotropy of selective laser-melted stainless steel: The importance of the rotation angle increment and the limitation window
journal, January 2018

  • Hitzler, Leonhard; Hirsch, Johann; Tomas, Josef
  • Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, Vol. 233, Issue 7
  • https://doi.org/10.1177/1464420718757068

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