Galvanized steel plate is to prevent the surface of the steel plate from being corroded and prolong its service life, a layer of metal zinc is coated on the surface of the steel plate.
According to the production and processing methods, it can be divided into the following categories:
Hot-dip galvanized steel. The sheet steel is immersed in a molten zinc bath, and a sheet of zinc is adhered to its surface. At present, it is mainly produced by continuous galvanizing process, that is, galvanized steel plate is made by continuously immersing the rolled steel plate in a plating tank where zinc is melted;
Alloy galvanized steel sheet. This kind of steel plate is also made by hot dip method, but immediately after it is out of the tank, it is heated to about 500 ℃ to form an alloy film of zinc and iron. This galvanized sheet has good paint adhesion and weldability;
Electro-galvanized steel sheet. The galvanized steel sheet produced by the electroplating method has good workability. However, the coating is thin, and the corrosion resistance is not as good as that of the hot-dip galvanized sheet;
Single-sided and double-sided differentially galvanized steel. Single-sided galvanized steel sheet, that is, a product that is galvanized on only one side. In welding, painting, anti-rust treatment, processing, etc., it has better adaptability than double-sided galvanized sheet. In order to overcome the disadvantage that one side is not coated with zinc, there is another galvanized sheet coated with a thin layer of zinc on the other side, that is, double-sided differential galvanized sheet;
Alloy, composite galvanized steel sheet. It is made of zinc and other metals such as lead and zinc to make alloys and even composite plated steel sheets. This kind of steel plate not only has excellent anti-rust performance, but also has good coating performance; in addition to the above five kinds, there are also color galvanized steel sheet, printing coated galvanized steel sheet, PVC laminated galvanized steel sheet, etc. But the most commonly used is still hot-dip galvanized sheet.
Galvanized sheet should have a good appearance, and should not have defects harmful to the use of the product, such as no plating, holes, cracks and scum, over-plating thickness, scratches, chromic acid dirt, white rust, etc. Foreign standards are not very clear about specific appearance defects. Some specific defects should be listed in the contract when ordering. Galvanized sheet steel products are mainly used in construction, light industry, automobile, agriculture, animal husbandry, fishery and commercial industries.