Abstract
Marangoni flow has a substantial influence on the quality of components fabricated via laser powder bed fusion (LPBF). However, Marangoni flow in melt pools is rarely quantified due to the opacity of liquid metals and the necessity for in situ evaluation. Here we report the findings of high-temporal-resolution synchrotron x-ray radiography experiments tracking the flow in the melt-pool. Dense, highly attenuating tungsten carbide particles are seeded within an elemental powder blend of aluminium and copper of varying composition. Due to the extremely high temporal resolution of greater than 50 kfps at the 31-ID-B beamline at the Advanced Photon Source, USA, we can track the position of tracer particles from frame to frame. This data provides valuable process guidance for optimising mixing and informs the development and validation of multiphysics models.
Highlights
Marangoni flow has a substantial influence on the quality of laser additive manufactured components
Marangoni flow has a substantial influence on the quality of components fabricated via laser powder bed fusion (LPBF)
We report the findings of our synchrotron x-ray radiography flow tracking experiments performed independently and without knowledge of the experiments by Guo et al [11]
Summary
Marangoni flow has a substantial influence on the quality of laser additive manufactured components. The understanding of the melt-pool flow nature is critical for microstructural and process control. Previous studies have deployed the use of highly attenuating tungsten tracers in x-ray experiments to track the melt-pool flow using high-speed synchrotron x-ray radiography [8] and using an innovative lab-source based stereographical apparatus [9] in arc welding and high power laser welding respectively. Guo et al [11] have reported the findings of their highspeed synchrotron radiographic studies of melt-pool flow tracking in AlSi10Mg and Al-6061. Guo et al [11], revealed a sharp contrast between the full field flow patterns under both conductionmode and keyhole-mode melting processing parameters. In conduction-mode, the melt pool was shown to exhibit a simple flow analogous to the glow platters typically observed in arc welding [8]. Marangoni flow dominates behind the laser whereas at and close to the laser-matter interaction site vaporization dominates the fluid flow along the keyhole walls
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