Galvanized steel plate factory

Galvanized steel plates may encounter various corrosion problems during use, which not only affect their aesthetics but may also seriously damage their service life and performance. The following is a summary of common corrosion problems in galvanized steel plate factory:

1. Oxidation of galvanized layer

1. White rust generation:
In humid environments, the galvanized layer on the surface of galvanized steel plates will first undergo oxidation, producing white basic zinc carbonate, also known as "white rust". The formation of white rust is a preliminary manifestation of corrosion of the galvanized layer. Although it still has a protective effect on the base metal (iron) of the steel plate, it will affect its appearance and subsequent processing and use.
2. Formation of black spots:

Over time, white rust will further react with impurity gases such as carbon dioxide in the air, producing black spots, known as "black spots". The formation of black spots marks a further deepening of the corrosion level of the galvanized layer.

2. Steel based oxidation

When the galvanized layer corrodes to a certain extent and loses its sacrificial anti-corrosion effect on the steel base, the steel base begins to oxidize, producing red rust. Once the steel base begins to oxidize, the corrosion rate will accelerate rapidly, and the service life of galvanized steel plates will be greatly shortened.

3. Special corrosion condition - blackening

1. The influence of elements in the galvanized layer:
After using galvanized sheet for a period of time, due to the influence of lead and other elements in the galvanized layer, the dull parts of the zinc flower will turn black. Although this situation still has a protective effect on the steel base, it will have a certain impact on its lifespan. However, with the improvement of galvanizing technology, such as discontinuing lead and using antimony to promote the formation of zinc flowers, this problem has been greatly improved.
2. Friction during transportation leads to:

During the transportation of galvanized sheet, if the steel strip layers are loose, the parts of the steel coil in contact with the pad wood will rub against each other and produce oxidation. After the white oxide is rubbed off, black spots will appear on the surface of the galvanized sheet. This situation will damage the passivation film, thinning the galvanized layer, thereby greatly reducing the lifespan and appearance quality of the galvanized sheet.

4. Electrochemical corrosion

In the atmospheric environment, the galvanized layer (zinc) and the base metal (iron) will form microbatteries under humid conditions. Zinc as the anode is preferentially oxidized and corroded, while iron as the cathode is protected. This process requires the participation of electrolytes (such as water films in the air), therefore it belongs to electrochemical corrosion. Electrochemical corrosion is the main corrosion mechanism of galvanized steel plates in atmospheric environments.

5. Corrosion caused by other factors

Galvanized steel plates have excellent corrosion resistance in dry or pollution-free environments, but their lifespan is greatly shortened in polluted environments. Chemical substances, particulate matter, and other pollutants in the polluted environment may cause damage to the galvanized layer and accelerate the corrosion process.
In summary, the common corrosion problems of galvanized steel plates mainly include oxidation of the galvanized layer (white rust, black spots), oxidation of the steel base, special corrosion conditions (blackening), and electrochemical corrosion. In order to extend the service life of galvanized steel plates and maintain their good performance, appropriate rust prevention measures such as oil coating and passivation treatment should be taken, and use in polluted environments should be avoided as much as possible.