(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, which does not have a visible spangle morphology and has a uniform surface coating.
(4) Zinc-iron alloy coating
The steel strip after passing through the galvanizing bath is heat treated to form an alloy layer of zinc and iron throughout the coating. This coating has a dark gray appearance without metallic luster. It is easy to pulverize during the violent forming process and is suitable for general In addition to cleaning, the coating can be painted directly without further treatment.
(5) differential coating
For both sides of the galvanized steel sheet, coatings with different zinc layer weights are required.
(6) Smooth skin pass
Smoothing is a kind of cold rolling of galvanized steel sheet with a small amount of deformation for one or several of the following purposes.
Improve the appearance of the galvanized steel sheet surface or be suitable for decorative coating; temporarily minimize the slip line (Lüdes line) or wrinkles produced when the finished product is processed.
For galvanized coils, the thin steel plate is immersed in the molten zinc tank, so that a thin steel plate with a layer of zinc is adhered to the surface. It is mainly produced by continuous galvanizing process, that is, continuous immersion of rolled 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, but immediately after it is discharged from 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.