Stipendiatstilling 14 SINTEF (2021-2023)

The project involves development of a method for accelerated material development of metals to be used in powder based additive manufacturing processes. The method consists of a combination of modeling and experimental work. The modeling part is focused on simulations of solidification at elevated temperature gradients to find suitable material candidates. Promissing alloys is thereafter processed with Arc Melting, a process with similar melting conditions as in additive manufacturing, but with the possibility to in-expensively and quickly screen a larger number of candidates. The as-solidified microstructure is thereafter investigated with optical microscopy and/or electron microscopy to obtain information about the solidified structure and its properties. So far, the method has been used on several aluminium alloys in the form of calculating at what point the columnar to equiaxed transition (CET) occurs. From those results a selection of alloys have been melted with the Arc Melter and analysed using an optical image analysis algorithm to find the grain size of the microstructure. A process model has been developed to connect the material aspect of the columnar to equiaxed transition for a material with the process parameters that are used in powder-based additive manufacturing. The model is tested for simple alloys and experimental work to connect to the model is complete. To connect the two models enables a rapid method of finding process parameters for a material where the equiaxed microstructure is favoured. A result is a refinement of the microstructure which could solve the issue of cracking in rapid solidification. Experimental results focus on the melt pool shape and size for each process parameter and examine the microstructure forming during solidification. The framework has also been applied on aluminium alloys with additions of nanoparticles with the intention to refine the grainstructure. The alloy with a selection of added nanoparticles was tested using the Arc Melting in which the most promising candidates were chosen for actual 3D printing. The results from the 3D printed compositions is not ideal but promising, and highlighted the importance of crucial aspects in the 3D printing process and which could be improved to obtain more dense results. The goal is to create a framework to effectively screen a large amount of alloys by covering many compositions and choose the ones that may give the best results, and by doing this eliminating poor candidates at an early stage of the full material development process.

Prosjektet har bidratt til utformingen av et eksperimentelt rammeverk som akselererer utviklingen av materialer og prosessparametre for pulverbasert additiv tilvirkning av aluminium. Eksperimentelle data har gitt basis for utvikling av mikrostruktur og prosessmodeller. Verktøyene er nyttig for videre utvikling av pulverbasert additiv tilvirkning som er en raskt fremvoksende teknologi med stort potensiale og flere bruksområder.