In-situ X-ray imaging reveals PBF-EB melt pool dynamics
Researchers from German institutions Friedrich-Alexander-Universität, Erlangen-Nürnberg, and Institute of Materials Physics, Geesthact and Sweden’s KTH Royal Institute of Technology, Stockholm, have published a paper in Additive Manufacturing focused on the use of in-situ imaging in Electron Beam Powder Bed Fusion (PBF-EB) Additive Manufacturing.
Despite the technology’s ability to process materials at >1000°C, a limited fundamental understanding of the intricate dynamics and melt pool formation has seen advanced processing strategies largely confined to experimental parameter studies. This has been because numerical models have mostly been unable to accurately predict processing conditions at the part or layer scale. In ‘In-situ synchrotron imaging of powder consolidation and melt pool dynamics in electron beam powder bed fusion’, the researchers performed high-speed in-situ X-ray imaging during multi-layer single track powder melting experiments on MiniMelt (a recently developed, custom-built PBF-EB machine for in-situ X-ray investigations).
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The paper noted several key melt pool formation dynamics, some of which the researchers state have been noticed for the first time. The imaging shows how melt pool formation involves the coalescence of molten powder particles into larger droplets and how these droplets either fuse with the melt pool or solidify as balling particles. Results are also said to elucidate the origins of melt pool oscillations and spatter formation and demonstrate how the superposition of the combined effect of these mechanisms can lead to chaotic and escalating movement within the melt.
In the abstract, the researchers noted, “We expect our results to improve and extend the phenomenological understanding of the powder consolidation mechanisms during PBF-EB and to aid in the development of new scanning strategies as well as the validation of numerical models.”
‘In-situ synchrotron imaging of powder consolidation and melt pool dynamics in electron beam powder bed fusion’ is available here.
