Magnetic modulation of keyhole instability during laser welding and additive manufacturing
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Keyhole instability during laser welding and laser powder bed fusion (LPBF) can cause keyhole collapse and pore formation. Using high-speed x-ray imaging, we demonstrate that the flow vortex–induced protrusion on the rear keyhole wall is crucial in initiating keyhole instability. Applying a transverse magnetic field suppresses the keyhole instability by driving a secondary thermoelectric magnetohydrodynamics (TEMHD) flow that alters the net flow vortex. This minimizes protrusions and large-amplitude keyhole oscillations. The suppression effectiveness depends on the laser scanning direction relative to the magnetic field orientation because this controls the Seebeck effect–induced Lorentz force’s direction. We show that at LPBF length scales, electromagnetic damping is weak, and for alloys with a large Seebeck coefficient, TEMHD becomes the dominant mechanism controlling flow behind the keyhole.
Date Issued
2025-02-21
Date Acceptance
2025-01-22
Citation
Science, 2025, 387 (6736), pp.864-869
ISSN
0036-8075
Publisher
American Association for the Advancement of Science (AAAS)
Start Page
864
End Page
869
Journal / Book Title
Science
Volume
387
Issue
6736
Copyright Statement
Copyright © 2025 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/39977505
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2025-02-20