The oxidation portion of the reaction
results
in the actual loss of metal
Fe <--> Fe+2 + 2 e- Step one (OX)
Fe+2 <--> Fe+3 + e- Step two (OX)
Fe <--> Fe+3 + 3 e- Overall
Oxidation half-reaction
The reduction portion of the reaction
drives the process of corrosion
O2 + 2 H20 + 4 e- <--> 4 OH- Reduction half-reaction