Page 248 - 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

Figure 7.10 presents the box-and-whisker plots of the results
obtained with pitting corrosion. When presented in this fashion, such
results can provide a useful spectrum of factor and subfactor
confidence levels for each possible corrosion form. Linking the
corrosion factors with possible forms of corrosion in this fashion may
provide guidance to inexperienced corrosion failure investigators
who have typically limited knowledge of corrosion processes.

Material factor Stress factor
+ +
0 2 4 6 8 10
0 1 2 3 4 5 6 7 8 9 10
Composition Applied stress
+ +
0 2 4 6 8 10 0 1 2 3 4 5 6 7 8 9 10
Crystal structure Residual stress

+ +
0 2 4 6 8 10 0 2 4 6 8 10
GB composition Product build-up stress
+ +
0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10
Surface condition Cyclic stress
Environment factor Geometry factor

+ +
0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10
Nominal environment Galvanic potentials
+ +

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 0 2 4 6 8 10
Circumstantial environment
Restricted geometries
Temperature factor
+
+
0 2 4 6 8 10
0 2 4 6 8 10 Settling of solids
Changing temperature
Time factor
+
+
0 1 2 3 4 5 6 7 8 9 10
Surface temperature
0 2 4 6 8 10
FIGURE 7.10 Box and whisker plots of the survey results obtained for the factors
and subfactors underlying the appearance of pitting corrosion.