Corrosion Rate Conversion
The following charts provide a simple way to
convert data between the most common corrosion units in usage, i.e. corrosion
current (mA
cm-2) , mass loss
(g
m-2 day-1
|
|
mA cm-2 |
mm year-1 |
mpy |
g m-2 day-1 |
|
mA cm-2 |
1 |
3.28 M/nd |
129 M/nd |
8.95 M/n |
|
mm year-1 |
0.306 nd/M |
1 |
39.4 |
2.74 d |
|
mpy |
0.00777 nd/M |
0.0254 |
1 |
0.0694 d |
|
g m-2 day-1 |
0.112 n/M |
0.365 /d |
14.4 /d |
1 |
-
where:
-
mpy = milli-inch per year
-
n = number of electrons freed by the corrosion reaction
-
M = atomic mass
-
d = density
-
Note: you should read the Table from left to right, i.e.:
1 mA cm-2 = (3.28 M/nd) mm y-1 = (129 M/nd) mpy = (8.95 M/n) g m-2 day-1
For
example,
if the metal is steel or iron (Fe), n =2,
M = 55.85 g and d =
7.88 g cm-3
and the Table of conversion becomes:
|
|
mA cm-2 |
mm year-1 |
mpy |
g m-2 day-1 |
|
mA cm-2 |
1 |
11.6 |
456 |
249 |
|
mm year-1 |
0.0863 |
1 |
39.4 |
21.6 |
|
mpy |
0.00219 |
0.0254 |
1 |
0.547 |
|
g m-2 day-1 |
0.00401 |
0.0463 |
1.83 |
1 |
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