Main forms of building metal corrosion

①Uniform corrosion. Corrosion of the metal surface makes the cross section evenly thin. Therefore, the average annual thickness loss value is commonly used as an indicator of corrosion performance (corrosion rate). Steel generally corrodes uniformly in the atmosphere.

②Hole corrosion. The corrosion of the metal points and forms deep pits. The occurrence of pitting is related to the nature of metal and its medium. Cavitation is prone to occur in media containing chlorine salts. Large hole depth is commonly used as the evaluation index. The corrosion of pipeline should be considered.

③Galvanic corrosion. Corrosion at the contact of different metals due to different electrical potentials.

④Gap corrosion. Local corrosion of metal surfaces in gaps or other hidden areas often occurs due to the difference in the composition and concentration of the medium between different parts.

⑤Stress corrosion. Under the combined action of corrosive medium and high tensile stress, the metal surface corrodes and expands inward into micro-cracks, often leading to sudden breakage. High strength steel bars (steel wires) in concrete can cause such damage.