New Metal Powders for Additive Manufacturing Including Co-free Maraging Steels & Copper Alloys for Space Technology

Conference Abstract: Metal powders, manufactured by gas atomization, provide sustainable, consistent quality & high-performance raw materials for many of the different additive manufacturing processes. Powder production based on melting processing that include high-volume induction melting, vacuum melting, directly integrated with gas atomization and refractory free electrode melting prior to gas atomization. Advanced material properties for each of the material families are highlighted, including titanium (Ti64) alloy with enhanced mechanical consistency developed by heat treatment & Hot Isostatic Pressing (HIP) and aerospace grades like Ti6242, which operate at higher temperatures. Cobalt alloys suitable for the production of dental prosthetic components, including partial removable dentures, copings, crowns & bridges and patient specific implant designs for orthopedic & maxillofacial reconstruction. Stainless steel alloy powders suitable for medical devices, surgical guides & tools. Maraging steels including ultra-high hardness grades (MAR-60) that benefit from in-situ heat treatment when deposited by Direct Energy Deposition (DED). Cobalt free maraging steels with equivalent performance to established materials (18Ni300/M300), in terms of hardness for mold tooling applications. And the superior corrosion resistance of Super Duplex 2507 stainless steel, printed by Laser- Powder Bed Fusion (L-PBF), compared to that of wrought material. Sinter based technology, such as green machining, metal based Fused Filament Fabrication (FFF) / Filament Deposition Modelling (FDM) and binder jetting require a balance of fine powder, typically less than 32 microns, while maintaining a degree of bulk flow. Required to provide a consistent layer thickness and bed density, which ultimately translates into high green & sintered part density. Finally, new metal powder product developments are presented that include extending the range of copper alloys for L-PBF that include grades relevant to space technology, specifically rocket nozzle applications, based on Cu-Cr-Zr & Cu-Cr-Nb, specifically GRcop42 developed by NASA.

Significance/Importance: The success of the metal Additive Manufacturing (AM) industry is completely reliant on the quality & range of alloys, especially metals in powder form. To create opportunities and applications that push the boundaries of performance of components, to levels that are not possible by conventional means. This can be achieved by combining the inherent design capabilities of AM, especially layer by layer building processes, and the selection of the build material. The range of alloys applied to AM have increased significantly in recent years. Drawing on a selection available as wrought products and existing powder metallurgy technologies, including Metal Injection Moulding (MIM). Alloy selection has been optimized for AM to combine performance & cost with ease of processing. Grades with low carbon equivalence, as similarities with micro-welding cannot be ignored, especially, in the case of laser based AM technologies. Material grades can also be applied to one or more applications, for example Ti6Al4V as application in both aerospace and medical applications. Where established & developing standards ensure design engineers have confidence in selection AM as the optimum root for production.
This presentation will provide an overview of the established materials, as well as new alloy powders available for the different AM processes, in terms alloy grade and powder size. Highlighting, printed material performance, for both static and dynamic applications, compared to conventional produced materials. Ultimately, AM components printed, using gas atomized powders, are shown to provide the required quality, performance and flexibility required for AM to create a sustainable future.