Due to its advantages of good mechanical properties, strong bearing capacity, easy manufacture, easy to adopt industrialized production, short construction and installation cycle and good sealing performance, the steel structure has been widely used in the national economy construction such as large-span structures (bridges, stadiums Roof truss,etc.), light steel structure (medium and large workshop), high-rise building (New York World Trade Center and Shanghai Jinmao Building, etc.), shell and shell structure (pressure vessel and long-distance pipeline). However, during service, the steel structure is prone to chemical, electrochemical or physical effects with the environment medium in which it is located, causing deterioration of the material and failure of the steel structure, which is often referred to as corrosion of the steel structure.