Neutrons identify internal stress in 3D printed parts

Air-cooled latticed turbine buckets operate at extreme temperatures and pressures within gas turbines. Their complex structure can be created additively, with selective laser sintering the technology widely used.

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"Complex components with such intricate structures would be impossible to make using conventional manufacturing methods like casting or milling," said Dr Tobias Fritsch, from the German Federal Institute for Materials Research and Testing (BAM).

Highly localised heat and the rapid cooling associated with laser sintering can lead to residual stress in components produced this way. During production, manufacturers usually address this issue with a downstream heat treatment process, but this additional step costs time and money. Using the Research Neutron Source Heinz Maier-Leibnitz (FRM II) at the Technical University of Munich (TUM), Fritsch and his colleagues were able to screen components for residual stress using non-destructive neutrons.

In a paper published in the Journal of Applied Crystallography, it’s described how Siemens Energy printed a lattice structure just a few millimetres in size using a nickel-chrome alloy typically used for gas turbine components. The usual heat-treatment after production was intentionally omitted.