Analysis and Application of Treatments to Mitigate Exfoliation Corrosion (Delamination) of 5XXX Series Aluminum
Navy STTR 2018.A - Topic N18A-T016 NAVSEA - Mr. Dean Putnam - dean.r.putnam@navy.mil Opens: January 8, 2018 - Closes: February 7, 2018 (8:00 PM ET)
TECHNOLOGY
AREA(S): Ground/Sea Vehicles ACQUISITION
PROGRAM: PEO LCS, PMS 501 LCS acquisition, and PMS 515 FF acquisition OBJECTIVE:
Research and develop chemical or non-chemical methods and processes to impart
surface morphology modifications to aluminum-magnesium (Al-Mg) alloys to
mitigate and increase the exfoliation corrosion resistance. DESCRIPTION:
5000-series marine grade aluminum alloys are used in high-speed,
high-performance ships and marine craft due to the many positive attributes
(high strength-to-weight ratio, weld-ability, and marine corrosion resistance)
of those alloys. Initial research in aluminum alloys for marine use indicated
that certain alloys and tempers could be made resistant to exfoliation corrosion.
Testing of these alloys and tempers was conducted for two years prior to
acceptance of those alloys and tempers for widespread use in the U.S. Navy.
Most of the Navy platforms, however, have service lives of 20-30 years and have
subsequently exhibited exfoliation corrosion. Exfoliation is a special type of
inter-granular corrosion that occurs on the elongated grain boundaries. The
corrosion product that forms has a greater volume than the volume of the parent
metal. The increased volume forces the layers apart, and causes the metal to
exfoliate or delaminate. Innovative approaches for processes that protect
against exfoliation are needed. Currently, when exfoliation corrosion occurs,
the Navy must remove and replace the affected plate, resulting in costly and
time-consuming maintenance actions. Prevention of exfoliation corrosion would
produce lifecycle cost savings and increase the operational availability of
ships and craft using 5000-series aluminum. PHASE
I: Research and develop applicable technologies that meet the overall objective
of the proposal with a focus on development, testing, and analysis of the
selected technology. The proposed research should include developing an
understanding of the physical mechanisms to improve the exfoliation corrosion
by altering the surface structure and morphology of the aluminum. Phase I
should include technology development, required testing, technical rationale
for the testing, analysis, project goals, milestones, and deliverables.
Address any hazardous material and environmental issues. The Phase I Option,
if awarded, will include the initial treatment specifications and capabilities
description to prototype the proposed solution in Phase II. Develop a Phase II
plan. PHASE
II: Based on the results of Phase I and the Phase II Statement of Work (SOW),
treat sample coupons and conduct short-term testing of those coupons. Take
measurements at each test point to determine if actual exfoliation or grain
boundary formation occurs as predicted. Coupon testing must occur at an ISO 9001:2015
certified facility. PHASE
III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to
Navy use. Identify all hardware, and develop all use documentation necessary
to implement the technology at manufacturing facilities. The proposed
technology is applicable to ship classes including the Littoral Combat Ship
(LCS), Ship to Shore Connector (SSC), and Ticonderoga-class (CG-47). REFERENCES: 1.
Brosi, J.K., et al. “Delamination of Sensitized Al-Mg Alloy During Fatigue
Crack Growth in Room Temperature Air.” Metallurgical and Materials Transactions
A, Vol. 34A, November 2012, 3952-3956. https://www.researchgate.net/publication/235355015_Delamination_of_Sensitized_Al-Mg_Alloy_During_Fatigue_Crack_Growth_in_Room_Temperature_Air 2.
Mohsen, S. et al. “Grain Orientation Effects on Delamination During Fatigue of
a Sensitized Al-Mg Alloy.” Philosophical Magazine Letters, Vol 95, Issue 11,
Nov 2015, 526-533. http://www.tandfonline.com/doi/abs/10.1080/14786435.2015.1110630?journalCode=tphl20 3.
Liao, M. et al. “Effects of Ultrasonic Impact Treatment on Fatigue Behavior of
Naturally Exfoliated Aluminum Alloys.” International Journal of Fatigue, 30
(2008), 717-726. http://www.sciencedirect.com/science/article/pii/S0142112307001715
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