1. Multiphysics Simulation Story: Simulation-LED Strategy for Corrosion Prevention
Naval Research Laboratory, Washington DC, USA
Siddiq Qidwai, Virginia DeGiorgi, and Nithyanand Kota

2. The Challenge
Corrosion is a multibillion dollar maintenance problem in the US
Corrosion in metals can lead to decreased strength causing material or component failure
Fundamental understanding pitting of corrosion is needed
How does pitting corrosion start and how to prevent it?
What is the effect of metal microstructure on pit growth?
Example of pitting corrosion in an aluminum alloy (top-down view). The formation of pits can reduce the strength of a material. Image courtesy of C. Feng and S. Policastro, NRL.

3. The Solution
Using multiphysics simulation, the effect of metal microstructure on pitting corrosion is being investigated
Establish relationship between metal microstructure, pit growth, and mechanical performance
Metal microstructure determined using orientation imaging microscopy at NRL
Use results to enable material designers to engineer materials that inherently prevent corrosion
Simulation results inspired the development of a new experimental method to evaluate corrosion at the micron scale
Required for model validation
At top, the model geometry implemented in COMSOL Multiphysics® including the metal microstructure. At bottom, the corrosion mechanism in steel and growth of an irregular corrosion front.

4. The Simulation Modeling pit growth in metals Simulation results
Incorporate microstructure of metal using LiveLink™ for MATLAB®
Determine corrosion potential as a function of crystallographic orientation for each grain
Corrosion rate based on potential at each location along the corrosion front
Moving mesh (ALE) technology for irregular corrosion front movement taking into account microstructure shape
Simulation results
Mechanical analysis reveals regions of high stress surrounding the pit
At top, plot of pit growth demonstrates the irregular corrosion front and shows the average metal concentration in the electrolyte. At bottom, von Mises stress in a metal affected by pitting corrosion.