Exploring the Feasibility of Using Cryomilled Aluminum Powder as Feedstock for Laser Powder Bed Fusion Additive Manufacturing
Technical Report,01 May 2019,01 Mar 2020
CCDC Army Research Laboratory Aberdeen Proving Ground United States
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Aluminum alloy 5083 AA5083 is an attractive candidate for many Army applications due to its high strength and corrosion resistance. The continuing development of additive manufacturing AM techniques enables design andor material changes to legacy parts, can contribute to the Armys efforts to manufacture lightweight vehicles and equipment, and helps drive interest in using parts made from high-strength aluminum Al alloys produced by powder-based AM. However, most Al alloys that are of interest for their mechanical properties, including AA5083, experience hot cracking during AM processes that makes these alloys unusable in most laser-based AM processes such as laser powder bed fusion LPBF. Current research has shown that one way to overcome hot cracking issues is by making changes to the chemical composition of the Al alloys, such as adding zirconium Zr or scandium Sc to AA5083. Alternatively, cryomilling AA5083 powder may be an alternative method to improve the performance of AA5083 during LPBF without the time and cost increases associated with alloy development. Cryomilling has been shown to lead to the incorporation of dissolved nitrogen and Al nitride as a solid solution within the Al matrix. These additions may behave like Zr or Sc and help alleviate the hot cracking issues during LPBF. In this study, as-atomized AA5083 powder was cryomilled in liquid nitrogen and welded with a laser to physically simulate the LPBF process. Changes in the powder morphology and chemistry from the cryomilling process led to powders that proved more weldable than the as-atomized powder and suggest feasibility for improved performance as a feedstock material for LPBF.
- Metallurgy and Metallography
- Manufacturing and Industrial Engineering and Control of Production Systems