Technically, corrosion is the tendency of any metal
to return to its most stable thermodynamic state.
Namely, that is the state with the most negative free
energy of formation. More simply stated, it is a
chemical reaction of the metal with the environment
to form an oxide, carbonate, sulfate, or other stable
compound. In most cases, using a different alloy,
material, proper coating, or impressed current can
prevent corrosion problems. When a metal part fails
in service, it is essential to determine the cause of
the failure so that the replacement part can be
manufactured from the proper alloy to prevent
future failure. Many times a failed part is replaced
with the same alloy. For example, if a piping system