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In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing

Leung, CLA; Marussi, S; Atwood, RC; Towrie, M; Withers, PJ; Lee, PD; (2018) In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing. Nature Communications , 9 , Article 1355. 10.1038/s41467-018-03734-7. Green open access

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Abstract

The laser–matter interaction and solidification phenomena associated with laser additive manufacturing (LAM) remain unclear, slowing its process development and optimisation. Here, through in situ and operando high-speed synchrotron X-ray imaging, we reveal the underlying physical phenomena during the deposition of the first and second layer melt tracks. We show that the laser-induced gas/vapour jet promotes the formation of melt tracks and denuded zones via spattering (at a velocity of 1 m s−1). We also uncover mechanisms of pore migration by Marangoni-driven flow (recirculating at a velocity of 0.4 m s−1), pore dissolution and dispersion by laser re-melting. We develop a mechanism map for predicting the evolution of melt features, changes in melt track morphology from a continuous hemi-cylindrical track to disconnected beads with decreasing linear energy density and improved molten pool wetting with increasing laser power. Our results clarify aspects of the physics behind LAM, which are critical for its development.

Type: Article
Title: In situ X-ray imaging of defect and molten pool dynamics in laser additive manufacturing
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41467-018-03734-7
Publisher version: http://dx.doi.org/10.1038/s41467-018-03734-7
Language: English
Additional information: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Keywords: Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, Powder-Bed Fusion, Stainless-Steel, Mechanical-Properties, Processing Conditions, Melting Process, Components, Behavior, Porosity, Alloys, Conductivity
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10049127
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