Surface stability in stress-assisted corrosion: a peridynamic investigation

Abstract

In this paper, the stability of corrosion front of metallic material under tension is investigated by using a stress-assisted corrosion peridynamic model. The electrolyte diffusion tends to smoothen the corrosion front, while the mechanical loading tends to roughen the corrosion front and leads to higher stress concentration. We introduce a critical stress, below which the roughness of the corrosion front does not blow up, and the corrosion front is stable. Real-time surface roughness evolution is utilized to find the critical stress. Numerical results for both initially convex/concave sinusoidal and random surface contours show that corrosion without stress flattens the corrosion front, and when stress is higher than a certain value, the stress-assisted corrosion makes the corrosion front rougher. The effect of mechanochemical coefficient and applied electrical potential on the critical stress is analyzed numerically. It is found that the critical stress is less affected by the external voltage than by the mechanochemical coefficient. We also apply the model for corrosion in metal with initial holes or insulate impurities, revealing that hard impurities, such as dispersed oxides, can help maintain the stability of corrosion front, thus reducing the risk of stress-corrosion cracking.