Additive Manufacturing —also known as 3D printing—is proving to be a game-changer for metal parts in many industries. Aerospace was an early adopter, but it also has applications for automobiles, medical devices, electronics, robotics and presents its own specific challenges – for example, development has focused on aluminium-silicon casting alloy compositions which are printable but have only moderate strength. Conventional high-strength aluminium alloys are not well-suited to additive manufacturing as they tend to crack during processing and require heat treatments including a fast cooling (quench) operation which can cause distortion of the complex, thin-walled geometries made possible by the Additive Layer Manufacturing (ALM) process. To meet the needs of our customers for better solutions to combine the intrinsic advantages of aluminium with the above new possibilities, Constellium sets about designing completely new alloys.
Constellium is partnering with a number of external parties across the additive manufacturing value chain. The new alloys Aheadd® HT1 and Aheadd® CP1 are a focus for several large consortium projects with major aerospace customers. A number of further collaborations are ongoing in sectors such as motorsport and satellites.
Constellium has developed two novel additive manufacturing aluminium alloys, specifically designed for laser powder bed additive manufacturing and bringing improved properties, higher ALM productivity and simplified post-process heat treatment.
Aheadd® HT1 is the most suitable additive manufacturing alloy for applications which need high strength and service temperatures up to around 250°C. Its high thermal stability makes it an ideal choice to replace selected titanium or steel additive manufacturing applications to reduce the component weight and cost. The higher thermal conductivity of aluminium over titanium may bring additional advantages.
Aheadd® CP1 is an additive manufacturing alloy packed with many features. High strength & ductility, excellent surface finishing characteristics, thermal and electrical conductivity approaching that of pure aluminium, very high printing speed and simplified post-processing make it the solution of choice for a wide range of aluminium additive manufacturing applications. Aluminium additive manufacturing heat exchangers are ideally suited to this alloy.
For both alloys, component properties can be adjusted by tuning the post-build stress-relief treatment. This simplifies post-processing by eliminating the need to solution treat, quench and age, and also minimizes the risk of distortion of printed components during post-processing
The new powders are now available for evaluation. Next steps include aerospace qualification studies as well as shorter-term developments for applications in motorsport or satellites. Scientific work with universities is focused on the interactions between the ALM process and the microstructure of the components, as well as the links between microstructure and component properties.