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

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 t...

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Bibliographic Details
Published in:Nature communications Vol. 9; no. 1; pp. 1355 - 9
Main Authors: Leung, Chu Lun Alex, Marussi, Sebastian, Atwood, Robert C., Towrie, Michael, Withers, Philip J., Lee, Peter D.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 10.04.2018
Nature Publishing Group
Nature Portfolio
Subjects:
147/135
639/301/1023/1026
639/301/930/1032
639/301/930/2735
Additive manufacturing
Beads
Flux density
Humanities and Social Sciences
Lasers
Melt pools
Migration
multidisciplinary
Science
Science (multidisciplinary)
Velocity
ISSN:2041-1723, 2041-1723
Online Access:Get full text
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Summary: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. Additive manufacturing of metals is now widely available, but the interaction of the metal powder with the laser remains unclear. Here, the authors use X-rays to image melt features and pore behaviour during laser melting of powders.
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ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-018-03734-7