Fan, Xianqiang, Fleming, Tristan G., Clark, Samuel J., Fezzaa, Kamel, Getley, Anna C. M., Marussi, Sebastian, Wang, Hongze, Lun Alex Leung, Chu, Kao, Andrew ORCID: https://orcid.org/0000-0002-6430-2134 and Lee, Peter D. (2025) Magnetic modulation of keyhole instability during laser welding and additive manufacturing. Science, 387 (6736). pp. 864-869. ISSN 0036-8075 (Print), 1095-9203 (Online) (doi:10.1126/science.ado8554)

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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.

Item Type:	Article
Uncontrolled Keywords:	magnetic field, additive manufacturing
Subjects:	Q Science > Q Science (General) T Technology > T Technology (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Computing & Mathematical Sciences (CMS)
Last Modified:	10 Mar 2025 16:50
URI:	http://gala.gre.ac.uk/id/eprint/49985

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