Galvanized coils have different surface conditions due to different treatment methods in the coating process, such as ordinary zinc coils, fine zinc coils, flat zinc coils, zinc-free coils, and phosphate surfaces. Galvanized coils should have good appearance and should not have defects that are harmful to product use, such as no plating, holes, cracks and scum, excessive plating thickness, scratches, chromic acid dirt, white rust, etc.
Alloyed galvanized steel coil. This kind of steel coil is also made by the hot dip method, but it is heated to about 500°C immediately after coming out of the tank to form an alloy film of zinc and iron. This kind of galvanized coil has good coating adhesion and weldability; single-sided galvanized steel coil and double-sided galvanized steel coil. Single-sided galvanized steel coils are products that are galvanized on only one side. In terms of welding, painting, anti-rust treatment, processing, etc., it has better adaptability than double-sided galvanized coils.
To overcome the shortcomings of one side not being coated with zinc, there is another type of galvanized coil that is coated with a thin layer of zinc on the other side, that is, a double-sided galvanized coil. The reason why the surface of the galvanized coil is coated with a layer of zinc on the surface of the steel is because it is also because steel plates are easily oxidized by water and other oxides in the air and thus corrode. Coating with a layer of zinc is actually to better protect the steel. The galvanized coil has two major advantages, one is adhesion and the other is weldability. It is precisely because of these two advantages that it has been widely used in construction, industry, automotive industry, and commerce. Another important feature is corrosion resistance, which can have a good effect on the manufacturing of home appliance casings.