TY  - JOUR
SP  - 864
VL  - 387
N1  - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions.
IS  - 6736
SN  - 0036-8075
UR  - https://doi.org/10.1126/science.ado8554
A1  - Fan, Xianqiang
A1  - Fleming, Tristan G
A1  - Clark, Samuel J
A1  - Fezzaa, Kamel
A1  - Getley, Anna CM
A1  - Marussi, Sebastian
A1  - Wang, Hongze
A1  - Leung, Chu Lun Alex
A1  - Kao, Andrew
A1  - Lee, Peter D
JF  - Science
EP  - 869
AV  - public
Y1  - 2025/02/21/
TI  - Magnetic modulation of keyhole instability during laser welding and additive manufacturing
PB  - American Association for the Advancement of Science (AAAS)
ID  - discovery10205876
N2  - 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.
ER  -