What are Pitting Corrosion
and Crevice Corrosion?
- Highly localized holes may be well separated
or so close they resemble a roughened surface.
- Corrosion products can mask them. One area of
surface becomes highly anodic or localized changes
occur in corrodent composition (at crevices).
- Microbiologically Induced Corrosion (MIC) is a
primary pitting producer. With SS, halides, (especially
chlorides) destroy the protective oxide film and cause
- Narrow openings, gaps between two metals (riveted seams,
bolt/washer) or a metal and nonmetal (0-ring, gasket, etc.)
Concentration cell is formed within the crevice. Tubercles --
local mounds of corrosion products -- form on a surface and
promote accelerated corrosion underneath, e.g., steel
and cast iron water supply system - pipes, tanks.
- The example below shows a heavily tuberculated 75 mm
(3-inch) outer diameter steel mill water supply line.