The electrochemical corrosion of metals in general is mainly oxygen absorption corrosion.
Positive reaction O2+4e—+2H2O=4OH—
Negative reaction Fe—2e—=Fe2+ 2Fe—4e—=2Fe2+
Overall reaction: Fe2+ +OH—=Fe(OH)2↓ 4Fe(OH)2 +O2+2H2O= 4Fe(OH)3
The metal is mainly stainless steel, and in humid air, a thin water film will be adsorbed on the surface of the steel. If this layer of water film is weakly acidic or neutral, oxygen can be dissolved and oxygen absorption corrosion occurs.
Hydrogen evolution corrosion can only occur in strong acidic environments such as sulfuric acid plants and acid rain environments.
