Johnstown, PA August 23, 2022
Concurrent Technologies Corporation (CTC) recently hosted a demonstration of the Laser Surface Modification (LSM) process for sensitization treatment of aluminum alloy ship structures. The demonstration was conducted as part of a project in which CTC is a subcontractor to the University of Virginia, supporting the prime contractor, Luna Labs USA, and the end client, the Naval Surface Warfare Center Carderock Division (NSWCCD). The demonstration was designed to determine the ability of a commercial laser to reduce sensitization of 5456 aluminum alloy on a mockup of a ship hull.
5xxx series aluminum alloys are a mainstay in modern ship construction and are commonly used across many platforms within the U.S. Navy fleet, but these alloys can become sensitized over time and at elevated temperatures (typically above 150°F [66°C]). Areas with a sensitized microstructure are susceptible to intergranular corrosion, exfoliation, and stress corrosion cracking when exposed to stress and corrosive media[1]. Weld repairs of cracks or inserts in sensitized aluminum material are challenging, time-consuming, and costly, because they require special arc weld treatments and procedures. Furthermore, no commercially available technologies have been developed to remediate an area that has become sensitized; the only current correction method for sensitized plate is to remove and replace the entire affected material, including removing and replacing all outfitting obstructing the repair.
CTC has supported the Navy in addressing issues with aluminum sensitization since 2010 and has supported the development and implementation of several devices to combat this insidious menace to ship structures[2]. Based on our expertise and prior work in the implementation of laser systems, Luna Labs USA teamed with CTC in order to evaluate the LSM processing technique to mitigate exfoliation corrosion of 5XXX series aluminum.
In March 2022, CTC hosted the laser surface treatment demonstration on the sensitized aluminum mockup at CTC’s facilities in Johnstown, PA. The team was honored to have personnel from NSWCCD and Commander, Navy Regional Maintenance Center in attendance, along with representatives from Luna, CTC, and Adapt Laser. During the demonstration, Adapt Laser personnel treated several areas of the mockup with the laser, using parameters determined by Luna. CTC then cut out the treated portions and provided them to Luna for testing and evaluation.
Key CTC Team members who made this demonstration a success included Tom Monito, Teresa Zawiskie, Larry Shirey, Jerry Stem, Bryan Thomas, Brenda Hancock, and Rob Mason.
This material is based upon work supported by NAVSEA under contract No. N68335-20-C-0346.
Any opinions, findings and conclusions or recommendation expressed in this material are those of the authors and do not necessarily reflect the views of NAVSEA.
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R. Mason, M. Phillippi, M. Smitherman, and D. Schario, “Strategies for the Mitigation of Aluminum Sensitization on U.S. Navy Ships,” Proceedings of the Fleet Maintenance and Modernization Symposium 2016, ASNE, 2016.
