Building expertise for additive repair

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Nuclear AMRC researchers have completed a detailed analysis of Inconel alloy for additive repair.

"DED is a flexible process for repair, with a lot of appeal to the aerospace and heavy engineering industries," says Udi Woy, technical lead for additive manufacturing at the Nuclear AMRC. "For applications of this size, flexibility is a significant factor. If you consider aero engine repairs, DED tools can be conveyed to the component, and material can be precisely deposited where it is required."

The Nuclear AMRC's research for Amos has focused on arc and laser DED with the nickel-chromium superalloy Inconel 718 in wire and powder form.

"We've developed a comprehensive matrix for the tensile, low-cycle fatigue and crack propagation testing of about 300 samples," Woy says. "This has enabled us to generate huge amounts of metallurgical data for quantifying the variations between conventional, as-built and repaired materials. We're also investigating the interface integrity, performance and predictability of these materials in different orientations, and how this data can facilitate the development of DED repair standards."

The Nuclear AMRC team are now working with samples featuring a series of intentional defects, produced by GKN Aerospace in Sweden. The samples have been scanned using an innovative inspection process developed by Canadian partners Liburdi and McGill University, and the Nuclear AMRC's non-destructive testing specialists are benchmarking the new technique against current practice.

"We're looking at how to automate the process of detecting defects to facilitate DED repairs," Woy says. "We can now identify certain types of defects such as voids and tool marks relatively easily, but cracks are more challenging."

A longer version of this article appeared in the Nuclear AMRC's Q4 2018 newsletter.