HASAM - Hypereutectic Alloys of Silicon and Aluminium for additive Manufacturing

I HASAM-prosjektet har man jobbet med 3D-printing av legeringer bestående av aluminium og silisium der innholdet av sistnevnte er høyere enn i konvensjonelle aluminium-silisium (AlSi) legeringer. Det er den raske avkjølingen i 3D-printeprosessene som muliggjør det høye silisiuminnholdet slik at man kan utnytte de egenskapene dette vil bringe med seg - som høyere slitestyrke, hardhet og bedre termiske egenskaper. Dette kan åpne for bruk av 3D-printede deler basert på AlSi legeringer som vil kunne ha vesentlig lavere vekt enn de konvensjonelle materialene samtidig som kravene til mekanisk styrke opprettholdes. Siden 3D-printing også muliggjør mer komplekse strukturer enn det som er mulig med vanlig støping vil man også her kunne oppnå de nødvendige egenskapene på styrke og samtidig potensielt kunne redusere vekt ytterligere på deler. I HASAM-prosjektet, støttet av Norsk Forskningsråd, er det utviklet et AlSi pulver produsert ved gassatomisering ved Elkem, Kristiansand. Pulveret har vist seg å være printbart i 3D-printere ved SINTEF, Trondheim hvor demodeler samt deler for måling av mekanisk styrke er blitt produsert. Prosjektet har demonstrert god styrke, slitasje- og korrosjonsbestandighet samt gode termiske egenskaper for de produserte AlSi-legeringene. For noen applikasjoner jobbes det videre med å bedre duktiliteten noe ved hjelp av en ytterligere optimalisering av sammensetning.

In the project important learnings have been made about the production of AlSi-powders for 3D-printing - both regarding securing a safe operation and a good quality and printability. Statistics have been gained on the performance of AlSi-alloys with high silicon content (35-40%) showing good results on strength, hardness, thermal properties, wear- and corrosion resistance while the elongation is still an issue for some applications with results of 1,5%. Based on the results from the project dedicated end user cases are suggested for a continuation of the project.

The objective of the 3-years project HASAM is to enable hypereutectic high silicon AlSi alloys for additive manufacturing (AM). Additive manufacturing and 3D-printing has after 30 years of R&D been established as a future growth market where many new value chains and eco-systems for suppliers and end-users have emerged and are still being developed. Some of these newly developed value chains are based on metal powders with a number of production methods available for the manufacture of complex-shaped components from various powdered alloys. The current metal AM market is characterized by a transition from prototyping to commercial series production of additive manufactured components, mainly made from commericial alloy powders containing iron, nickel, chromium, titanium, or other widely used foundry elements. Hypereutectic Al-Si alloys have excellent properties with many potential applications, but its commercial deployment is hindered by problematic challenges in production. As additive manufacturing builds parts directly without the need for casting, and with excellent control of the microstructure, AM is a perfect candidate technique for realising the potential fo hypereutectic Al-Si alloys. The next major implementation phase in metal additive manufacturing will undoubtly involve huge R&D efforts to develop new and specialized or tailored powder materials targeted for use in metal additive processes. Among the alloy systems to be further specialized for AM are the Al-Si system. This project will aim at developing an industrial production of additively manufactured hypereutectic Al-Si components, and to identify end-user applications and material requirements for 3D printed components made from such powder. A general effect of the HASAM project will be to contribute to an increased usage and flexibility of Al-Si alloys for AM and a potential broadening of the market for Al-Si powdered alloys. The project partners are Elkem, Hydro, Hycast and Sintef.