Several Main Factors Affecting Galvanized Sheet Corrosion

1. The corrosion process of galvanized sheet

During the entire service cycle of galvanized sheet, the first corrosion that occurs is the oxidation of the galvanized layer on the surface. After a longer time to generate "white rust", the "white rust" on the surface further reacts with impurity gases such as carbon dioxide in humid air. Generates "black spots". When the galvanized sheet is used for a long time and the galvanized layer corrodes seriously, the steel base loses the "sacrificial anti-corrosion" effect of zinc, and begins to oxidize, resulting in "red rust". Once the steel base begins to oxidize, the corrosion rate becomes rapid and the galvanized sheet ends its life.

Second, the main factors affecting the corrosion of galvanized sheet

1. Relative humidity

The amount of water vapor in the air is expressed as humidity. When the temperature is constant and the relative humidity is low, the corrosion is very slow; when the relative humidity gradually increases and reaches a certain limit, the corrosion rate suddenly increases significantly.

2. Temperature

Under certain humidity conditions, when the metal is corroded, the rate of corrosion increases to about 2 times for every 10C increase in temperature. When the temperature is greatly reduced, it will cause condensation on the metal surface, resulting in accelerated corrosion. For example, when the temperature difference between day and night is large, or the temperature difference between indoor and outdoor is large, condensation will occur. Rusting is most severe when condensation occurs periodically. Metal corrosion is most likely to occur in humid and mildewed areas, especially in hot, rainy or foggy areas or in seasons with high relative humidity.

3. Oxygen

Moisture and oxygen are the main factors of metal corrosion in the atmosphere. The water film layer adsorbed on the metal surface in the atmosphere is very thin, and oxygen is easily dissolved and penetrated, which makes the depolarization process of oxygen proceed quite smoothly, and plays a major role in atmospheric corrosion.

4. Pollution factors

Metals can also corrode quickly at lower relative humidity when there is pollution in the air or when the metal surface is dirty. As the humidity continues to rise at the critical relative humidity, the corrosion rate also increases gradually.