Metal

Selective laser melting

Engineering

Pure mathematics

Metallurgy

Materials science

Field (mathematics)

In situ

Melt flow index

Polymer

Mechanical engineering

Laser

Physics

Organic chemistry

Mathematics

Optics

Flow (mathematics)

Copolymer

Microstructure

Synchrotron

Composite material

Chemistry

Meteorology

Mechanics

Additive manufacturing

Melt flow plays a critical role in laser metal additive manufacturing, yet the melt flow behavior within the melt pool has never been explicitly presented. Here, we report in-situ characterization of melt-flow dynamics in every location of the entire melt pool in laser metal additive manufacturing by populous and uniformly dispersed micro-tracers through in-situ high-resolution synchrotron x-ray imaging. The location-specific flow patterns in different regions of the melt pool are revealed and quantified under both conduction-mode and depression-mode melting. The physical processes at different locations in the melt pool are identified. The full-field melt-flow mapping approach reported here opens the way to study the detailed melt-flow dynamics under real additive manufacturing conditions. The results obtained provide crucial insights into laser additive manufacturing processes and are critical for developing reliable high-fidelity computational models.

In-situ full-field mapping of melt flow dynamics in laser metal additive manufacturing