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Laboratory and Field Measurements of Corrosion and Stress Corrosion Cracking of AA5456-H116 for Validation of a Maintenance Prediction Model

Presenters Name: 
Gabriel Mallari
Co Presenters Name: 
Primary Research Mentor: 
Robert Kelly
Secondary Research Mentor: 
Gregory Kubacki
9:30 - 10:15
Time of Presentation: 
2019 - 9:30am to 10:15am
Newcomb Hall Ballroom
Presentation Type: 
Presentations Academic Category: 
Grant Program Recipient: 
USOAR Program

The U.S. Navy has recently been increasing the use of aluminum alloys in their naval vessels due to the high specific strength, weldability, and reasonable cost of these alloys. Despite these benefits, during exposure to aggressive ocean environments during service, these alloys are susceptible to sensitization, which is the formation of highly reactive particles in the alloy. This sensitization makes ship structures vulnerable to Intergranular Corrosion (IGC) and Intergranular Stress-Corrosion Cracking (IGSCC), which can result in the failure of ship components requiring additional maintenance costs and reduced operational readiness. Because IGC is unavoidable, it is essential to have a means of modeling the corrosion rates. Currently, the Office of Naval Research is developing a model to predict IGC and IGSSC rates to better plan for major maintenance events and proactively address issues. We are generating data of IGC and IGSCC rates under accelerated laboratory conditions as well as under service environments to support this model. We found a relationship between IGC and IGSCC propagation rates between samples exposed to cyclic salt-spray testing for 100hr and those exposed to service environments for up to 10 months aboard a Navy vessel. Taking advantage of this relationship in the future, we will be able to quickly generate data for more efficient model validation. This model may serve as a catalyst for further research in the IGC and IGSCC in other forms of transportation such as cars and airplanes.