Fabrication of Large-Scale, Light-Weight Aerospace Structures via the MELD Process

Various metal deposition processes have been used for the additive manufacturing (AM) of metals for more than a decade now. However, there is still a need for an economically viable AM technology which can offer good mechanical properties, flexibility in terms of material compatibility, and a viable path towards scaling up to meet the demand of manufactures who want to print large structural aerospace components in light-weight alloys. With few exceptions, most melt-based metal AM processes require the use of some combination of a powder bed, vacuum chamber, and/or inert environment. As the size of the parts scale up, the cost and complications associated with making them via AM increases to a point where it is either physically or economically not viable. The MELD process is a large scale open-atmosphere 3D metal AM technology with very high deposition rates and tremendous flexibility in material compatibility. A solid-sate technology, MELD fabricates metal parts without melting, avoiding melt related issues such as porosity and hot-cracking, and yields fully-dense parts without post-processing. Because the MELD process is solid-state the resultant printed parts exhibit very little effects related to residual stresses which often plague larger scale parts made via metal AM. This presentation will review applications where the MELD process is being used to fabricate large-scale aerospace structures such as rings with an outer diameter larger than 50 inches using both aluminum (2XXX, 6XXX, and 7XXX series) and magnesium alloys (WE43, AZ31, AZ61, AZ91). This presentation will present process parameters and conditions as well as the resultant microstructures, mechanical properties, and images of the fabricated components.