Magnetic modulation of keyhole instability during laser welding and additive manufacturing

• 成果类型: Article
• 署名作者: Fan, Xianqiang; Fleming, Tristan G.; Clark, Samuel J.; Fezzaa, Kamel; Getley, Anna C. M.; Marussi, Sebastian; Wang, Hongze; Leung, Chu Lun Alex; Kao, Andrew; Lee, Peter D.
• 署名单位: University of London; University College London; Queens University - Canada; United States Department of Energy (DOE); Argonne National Laboratory; Shanghai Jiao Tong University; Shanghai Jiao Tong University; University of Greenwich
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8902
• DOI: 10.1126/science.ado8554
• 发表日期: 2025-02-21
• 页码: 864-869
• 关键词: porosity formation; aluminum-alloy; field

摘要

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.