How Dangerous Can Localized Corrosion Be? An Experiment that Studies Its Effects R. Celdran and P. Gonzalo Universidad Autirnoma de Madrid, 28049 Madrid, Spain
Localized corrosion is one of the most frequent and severe forms of metal corrosion.' The concept of localized corrosion is based on a metal surface that a t some time during its exposure to a corrosive en5,ironment experiences attack at une or more sites. The attack remains confined to a limited number of sites, the area of which is small in comparison with the hulk surface. The attack is characterized by a high rate of metal loss, which can result in rapid penetration of the component concerned. Thus, a low overall metal loss when constrained to a small area can lead to comnonent failure in a short time. Localized corrosion cells may b e of a of the metal chemical nature. caused hv . varvine . -cornnosition . (galvanic cells) or the corroding solution (concentration cells) or of metal surface (active-passive cells). They may he also of physical nature. Some characteristic features of localized attacks are the following: anodes and cathodes separated, anode
