|About this Abstract
||MS&T22: Materials Science & Technology
||Advanced Materials for Harsh Environments
||Stress Corrosion Mitigation in Al-Mg via Zn-Rich Primers and Long-Term Performance Stability
||Matthew McMahon, Eric Dau, Allison Akman, Fatou Cisse
|On-Site Speaker (Planned)
The Al-Mg alloy AA5456 achieves a unique combination of weldability, general marine corrosion resistance, and high strength-to-weight ratio when utilized at relatively low temperatures in service. However, prolonged exposure to temperatures of at least 40ᵒC promotes Mg diffusion to the grain boundaries to form the highly anodic β phase in a process termed sensitization, which promotes stress corrosion cracking (SCC) and premature failure in seawater conditions. Previous work demonstrated that inorganic Zn-rich primers have a unique capability to provide stable, long-term cathodic protection that reduces the β phase corrosion rate and mitigates SCC in full immersion conditions. This work evaluates the maintenance of ZRP polarizability and cathodic protection performance over extended seawater and UV exposure, and quantifies the impact of primer degradation on the level of SCC mitigation achieved on highly sensitized AA5456. Testing is conducted in full immersion and alternate immersion conditions to more accurately simulate marine service conditions.