The Amos consortium completed extensive testing and development of selected direct energy deposition (DED) additive techniques using three widely-used aerospace alloys – Ti-6Al-4V, Inconel 718, and AerMet100 – in both wire and powder form.
These DED techniques combine laser or tungsten arc welding tools with automated or robotic control to accurately deposit and melt metal powder or wire. Many of these techniques are already used in aerospace and other industries to build parts to near-net shape, but are not yet widely used for repairing damaged components.
Several of the Amos partners have established experience and capabilities in these DED processes, and carried out extensive research to better understand their effects on the structural integrity of repaired components.
Numerous technical and commercial challenges have to be overcome before these processes can be used for safety-critical repairs. These include variations in equipment and processing capabilities, and in the properties of the material produced – for example, the deposited material can be strongly anisotropic depending on how it is deposited.
All tests carried out in the project were done to the relevant ASTM standard. Tests included:
- Visual and dimensional checks (visual and metrology).
- NDE (CT scans and fluorescent penetrant inspection).
- Macro and micro-analysis (microstructural analysis, porosity).
- Chemical analysis (X-ray fluorescence).
- Mechanical testing (tensile, low cycle fatigue, crack propagation).
Tests were completed on the substrate, the as-built material, and the interface of the substrate and deposited material. Overall, wire samples performed better than powder samples under typical loading conditions.
Normalised data from these tests have been gathered into a database to support further process development.