Structural, ballistic, and mobility requirements have led to the selection of aluminum alloy 2519 as the primary structural material for the Advanced Amphibious Assault Vehicle (AAAV). AI 2519 is a relatively new copper precipitation-strengthened alloy designed for strength and ballistic properties. There is very little seawater corrosion data for this alloy but the composition and recent test results suggest that it will show susceptibility to pitting in marine environments.
Two-year seawater alternate immersion exposures of welded AI 2519 panels with and without protective coatings were conducted to simulate the expected AAAV service environment. Results show that unprotected AI 2519 is susceptible to uniformly dispersed, shallow pitting under these conditions. Deeper pitting occurred under coating failures. No accelerated attack of the weld metal or heat affected zones was observed. Cathodic protection applied during the immersion cycles drastically improved performance of all the coatings and reduced the corrosion rate of the unprotected material.
The Advanced Amphibious Assault Vehicle (AAAV) is currently undergoing final design for the United States Marine Corps (USMC) and prototypes are in test. This vehicle is intended to replace the existing fleet of Amphibious Assault Vehicles (AAV) while providing significant waterborne and land operational performance enhancements. Due to the nature of the amphibious mission and the performance attributes of the AAAV, the environment in which it will operate can be expected to be the most corrosive of any existing USMC vehicle system. As a result, the Marine Corrosion Branch, Naval Surface Warfare Center, Carderock Division (NSWCCD) is conducting a test program aimed at mitigating corrosion and minimizing maintenance associated with corrosion.