Page 401 - Corrosion Engineering Principles and Practice

370 C h a p t e r 9 A t m o s p h e r i c C o r r o s i o n 371

FIGURE 9.43 Coated panels exposed on an atmospheric test rack in a
marine environment with CLIMAT coupons for corrosivity calibration.
(Courtesy of Defence R&D Canada-Atlantic)
of the metal surfaces during the first few days of exposure may affect
the initial corrosion rate, or average weather conditions may not be
encountered during the initial exposure period.
Some tests are continued until failure, as in SCC testing. However,
in tests of protective coatings, as well as in others, periodic measure-
ments of typical properties such as degree of undercutting are more
adequate (Fig. 9.43).

9.7 Corrosion Behavior and Resistance
The following sections contain a brief description of the atmospheric
corrosion performance of some metallic materials commonly used in
atmospheric conditions.

9.7.1 Iron, Steel, and Stainless Steel
Iron, in its various forms, is exposed to all kinds of environments. It
tends to be highly reactive with most of them because of its natural