Galvanizing is the reaction of molten metal with an iron substrate to produce an alloy layer, there by combining the substrate and the plating layer. Hot-dip galvanizing is to pickle iron and steel parts first. In order to remove iron oxide on the surface of
iron and steel parts, after pickling, it is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed solution of ammonium chloride and zinc chloride.And then sent to the hot-dip plating bath. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.

According to the production and processing methods, it can be divided into the following categories: 1. Hot dip galvanized steel sheet. 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 rolled steel plates in a plating tank where zinc is melted;

2. Alloy galvanized steel sheet. This kind of steel plate is also made by hot-dip method, but after it is out of the tank, it is heated to about 500 ℃ immediately to form an alloy film of zinc and iron. This galvanized sheet has good paint adhesion and weldability; 3. 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;

3.Single-sided and double-sided differential 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; 5. Alloy, composite galvanized steel sheet. It is made of zinc and other metals such as aluminum, lead, zinc, etc. to make alloys or even composite plated steel plates. This kind of steel plate not only has excellent anti-rust performance, but also has good coating performance;

4. In addition to the above five types, there are also colored galvanized steel sheets, printed and painted galvanized steel sheets, and PVC laminated galvanized steel sheets. But the most commonly used is still hot-dip galvanized sheet.