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

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.

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.

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.