Galvanized coil is a thin steel sheet in which a thin steel sheet is immersed in a molten zinc bath to adhere a layer of zinc on the surface. It is mainly produced by continuous galvanizing process, that is, continuous immersion of coiled steel sheets in a galvanizing tank with molten zinc to make galvanized steel sheets; alloyed galvanized steel sheets. This kind of steel plate is also manufactured by hot dipping method, but immediately after leaving the tank, it is heated to about 500°C to form an alloy film of zinc and iron. This galvanized coil has good paint adhesion and weldability.

(1) Normal spangle coating

In the normal solidification process of the zinc layer, zinc grains grow freely to form a coating with obvious spangle morphology.

(2) minimized spangle coating

During the solidification of the zinc layer, the zinc crystal grains are artificially restricted to form the smallest possible spangle coating.

(3) Spangle-free coating

It is obtained by adjusting the chemical composition of the plating solution, does not have a visible spangle morphology, and has a uniform surface coating.