Corrosion, its progress and its effects can be studied with Atomic Force Microscopy.

As one example we did a study of the start and early progression of corrosion on samples of carbon steel taken after exposure to dry steam.

Height and phase image of carbon steel after a brief exposure to
dry steam.  In the height image (left panel) the bright areas are
high and the dark areas are low.  The corrosion starts as small
plaques forming in hollows within the material (bright regions
in the phase image).
After a somewhat longer exposure, the corrosion has spread to
cover most of the surface. Small patches of as yet uncorroded
material are visible as dark spots in the phase image.

By providing detailed information on the development and progress of corrosion, AFM allows for process and material improvements to reduce corrosion and improve product life.