English to Russian Tech/Engineering Engineering (general)

Lateral undercutting corrosion at a scratch in the paint, or at a sheared edge (where the paint/primer/metallic coating/steel are all exposed to potential corrosion).

Undercutting corrosion of a scribed surface during testing is an indication of poor paint performance. The net effect of this lateral undercutting corrosion is the loss of adhesion between the paint and the metal substrate. This particular type of corrosion can be quite damaging since it combines all the elements of a crevice corrosion scenario, i.e. small local anode/large external anode, formation of an acidic environment, production of gaseous hydrogen.

http://corrosion-doctors.org/PaintCoatings/undercutting.htm