The steel structure To the steel structure, the speed of corrosion is mainly relate to the air relative humidity and the composition and quantity of pollutant in the atmosphere. In order to reduce metal corrosion and extend its service life, we must adopt the spreads brushes and spray finishing methods after operate the surface treatment, to form the protective film in the metal surface, and cause the metal and the corrosive medium isolates, thus prevents the metal the corrosion.