Multi-Layer Approach for Corrosion Resistance of Aircraft Aluminum Alloys

The objective of this proposed Phase I study is to develop an alternate production practice for high-strength aircraft aluminum alloys via an experimental layering process in order to enhance stress corrosion cracking (SCC) resistance. The basic operational processing procedure is to produce aluminum through roll bonding of a composite of several layers of standard material such that the grain shape/orientation alternates through the through-thickness plane of the finished plate. It is known from the literature that stress-corrosion cracking will propagate in the short-transverse direction and to some degree in the long transverse direction. The intent of this investigation will be to determine whether a layering of previously processed aircraft plate in 0-90 and 0-45 orientations can result in a microstructure that will inhibit the progress of SCC damage through the thickness plane of the plate material. The experiment will compare three conditions: i) standard process aircraft alloys, ii) cross-rolled aircraft material, and iii) layered material produced from standard un-clad aircraft plate. If the Phase I effort is successful, more extensive testing and scale-up attempts will take place during Phase II.