Knowledge of steel structure anticorrosion

(1) Atmospheric corrosion

atmospheric corrosion of steel structures is mainly caused by chemical and electrochemical action of water and oxygen in the air. Water vapor in the atmosphere forms an electrolyte layer on the metal surface. Oxygen dissolved in the air acts as cathode depolarizer. Both of them form a basic corrosion galvanic cell with steel components. The corrosion products will affect the electrode reaction of atmospheric corrosion when the surface of steel components is corroded by atmosphere to form a rust layer. Local corrosion

(2) Local corrosion

Local corrosion is the most common in steel structure buildings, mainly galvanic corrosion and crevice corrosion. Galvanic corrosion mainly occurs at different metal combinations or joints of steel structures, in which the metal with negative potential corrodes faster, while the metal with positive potential is protected, and the two metals constitute corrosive galvanic batteries.

Crevice corrosion mainly occurs in the surface crevices between different structural parts of steel structure and between steel members and non-metals. When the crevice width allows liquid to stagnate in the crevice, the most sensitive crevice width of steel structure is 0.025-0.1 mm. Stress corrosion