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) and penetration rates (mm y^-1 or mpy) for all metals or for steel

• 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:

Note: you should read the Table from left to right, i.e.:

1 mA cm^-2 = 11.6 mm y^-1 = 456 mpy = 249 g m^-2 day^-1