Page 249 - Corrosion Engineering Principles and Practice

222 C h a p t e r 7 C o r r o s i o n F a i l u r e s , F a c t o r s , a n d C e l l s 223

Uniform Pitting Crevice Galvanic Erosion Cavitation Fretting Intergranular Dealloying SCC Fatigue Scaling Internal attack

Material
Composition
Crystal structure
GB composition
Surface condition
Environmental
Nominal
Circumstantial
Stress
Applied
Residual
Product build-up
Cyclic
Geometry
Galvanic potentials
Restricted geometries
Settling of solids
Temperature
Changing temperature
Temperature of surface
Time
Changes over time
Based on response where x >7 and s<3
FIGURE 7.11 Results of compiled survey of corrosion experts highlighting the
most important correlations between corrosion forms and factors.

A listing of the most important factors should therefore improve
the level of awareness on the complexity and interaction of the
variables behind most corrosion failures. Some knowledge of how
the experts have reduced such complexity to a reduced set of variables,
as the compiled results of the survey indicate in Fig. 7.11, may also
help to focus an investigation on the most important variables behind
a specific corrosion case.
An application of the compiled framework could be to test one’s
skills against the experts as illustrated in Fig. 7.12. Another applica-
tion of this practical correlation would be to use the framework of
factors versus forms for archiving data in an orderly manner. Analy-
sis of numerous corrosion failure analysis reports has revealed that
information on important variables is often lacking [13]. The omis-
sion of important information from corrosion reports is obviously
not always an oversight by the professional author. In many cases,
the desirable information will simply not be (readily) available and
require a special investigation to be completed.