A test method is in development to assess aerospace coatings and their capacity to protect structures
from environmental assisted cracking (EAC) initiation and propagation in corrosive atmospheres. EAC
initiation and propagation is influenced by the complex interactions of load, environment, and alloy
properties. These are explored and defined to produce a method that quantifies the crack initiation
resistance provided by protective coatings for high strength aluminum alloy 7075-T651, enabling
comparison between coatings. Accurate assessment of coating performance will reduce the risk
associated with introducing new environmentally compliant coatings. Conventional immersion EAC
testing is not well suited to study factors and interactions leading to atmospheric EAC because the bulk
electrolyte conditions for immersion testing are different from those of a thin-film electrolyte. A
controlled corrosive environment, unique test article geometry, static loading condition, and
continuously monitoring sensor system are employed to measure onset and propagation of cracking
under atmospheric conditions. Initial results demonstrate a strong dependence on inhibited primer type
and galvanic coupling.