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Technical approach for creating corrosion design guide for nickel alloy 625.
The goal of this project is to quantify the susceptibility of AM parts to corrosion and related effects of post processing.
Unexpected corrosion performance of alloys for additive manufacturing (AM) results from the unique processing conditions such as rapid solidification, complex thermal cycles, and rough surface finish. The range of potential post processing steps further complicates the problem, and the institutional and documented knowledge of corrosion in castings, forgings, welds, and powder metallurgy products is not directly applicable to AM. The lack of authoritative localized saltwater corrosion performance data for AM alloy 625 constrains adoption of AM and ultimately limits operational readiness because corrosion cannot be effectively considered in component design. The underlying physical processes governing corrosion of additively manufactured alloys and the AM and post-build process parameters affecting corrosion are not well understood, limiting any lessons learned to one alloy and one corrosion mechanism.
The objective of this project is to develop authoritative data and new knowledge regarding the corrosion of AM material into a corrosion performance design guide for AM nickel-based alloy 625. The effort seeks to generate authoritative, high quality stress corrosion cracking, crevice corrosion, and galvanic corrosion data (e.g. time-to-failure and corrosion rate) for alloy 625 and to understand the unique corrosion mechanisms of AM alloy 625 compared to cast and wrought alloy 625 using novel corrosion experiments.
The project team includes 3D Systems, Newport News Shipbuilding, University of Akron, and Northrop Grumman. Processing conditions, furnace heat treatments, and surface modification techniques are being varied to produce different surface roughness and microstructure characteristics for testing to determine the structure effects on corrosion properties. The team is using the test results to generate corrosion data for a corrosion performance design guide for AM Ni-base