General Corrosion - is usually considered to be less problematic than localized forms of attack. This is because it is reasonably easy to predict the rate of penetration, and a "corrosion allowance" (additional metal or alloy) can be added during the design process.
The location of both anodes and cathodes is random with respect to time during General Corrosion. As a result, a repetitive cycle in which anodes become cathodes - and then revert to being anodes again - is established. Consequently, on a macro scale the surface appears to corrode uniformly.
On a micro scale, the surface is not uniform. It is composed of "terraces" that are separated by monatomic (consisting of one atom) high "ledges". These ledges contain "kink sites" that also have dimensions of one atom. The terraces have the highest coordination number - followed by ledges - followed by kink sites. As kink sites have the lowest coordination number, they are least strongly bound to the surface of the metal. As a result, kink sites are most likely to be removed during corrosion.
