Understanding the Interactions of Multiple Pits Under Freely Corroding Conditions

• Published in: Journal of the Electrochemical Society 2024-12, Vol.171 (12)
• Main Authors: Katona, R. M., Roop, M. L., Venkatraman, A., Montes de Oca Zapiain, D., Schaller, R. F.
• Format: Article
• Language: English
• Subjects: atmospheric corrosion; corrosion modeling; localized corrosion
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ad9415

The interactions of two propagating pits on a single cathode surface were evaluated across variations in chloride concentration, water layer (WL), pit sizes, separation distance (x2), and cathode size (LCath) under freely corroding conditions using finite element methods (FEM). FEM current was utilized to predict stability based on the Galvele pit stability product. FEM predictions were utilized to train a neural network machine learning model for rapid stability predictions. Pit one is in the center of a circular cathode while pit two moves radially from the center pit. With two pits, the overall current in each is decreased with respect to a single pit, however, the total current is increased. Increasing WL and LCath generally increased overall current in each pit and increased predicted maximum pit sizes. Increasing x2 decreased current in pit two due to less cathode being available to support dissolution in proximity to pit two. Increasing chloride concentration from 0.6 to 3 M NaCl increased current, while increasing from 3 to 5.3 M NaCl decreased current. An overall increase in predicted pit size with increase in chloride concentration is predicted. A model was created to predict current and maximum pit size and captured underlying physics and predicted stability across the multidimensional parameter space