Influence of a Paint Coating and Water Displacing Corrosion Inhibitor (WDCI) Application on the Stress Corrosion Cracking (SCC) Behavior of Aluminum 7075 Alloy

摘要

The influence of a low chromate and a high chromate paint system and a water displacing corrosion inhibitor (WDCI) on the stress corrosion cracking (SCC) of an aluminum 7075-T651 alloy was investigated. Bolt-loaded double cantilever beam specimens were tested in a salt spray environment. Results show that a paint coating or a WDCI-film promote a plateau region in the crack growth rate curves. This is possibly caused by the fact that for coated specimens the cathodic reactions are becoming rate controling, due to the limited area available for the cathodic processes. Although neither a paint coating nor a WDCI-film prevents SCC completely in precracked specimens, the crack growth rate may be reduced by a low chromate paint system or a WDCI. Crack growth rate increases when a high chromate paint system is used.