Galvanized coil is a thin steel sheet with a layer of zinc adhered to the surface by immersing a thin steel sheet in a molten zinc tank. At present, it is mainly produced by the continuous galvanizing process, that is, the coiled steel sheet is successively immersed in a galvanized bath with molten zinc to make a galvanized steel sheet; alloyed galvanized steel sheet. 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 outstanding paint adhesion and weldability.
The galvanized layer of the galvanized coil is passivated, which can reduce the folding and rust (white rust) under the condition of storage and transportation at moisture temperature. However, the anti-corrosion function of this chemical treatment is limited, and it hinders the adhesion of most coatings. This kind of treatment is generally not used on the zinc-iron alloy coating. Except for smoothing the surface, as a routine, the manufacturer performs passivation treatment on other types of galvanized coatings.
The colorfully coated steel plate using galvanized coil as the substrate, in addition to zinc protection, the organic coating on the zinc layer has a covering and isolation effect, which can prevent the steel plate from rusting, and has a longer service life than galvanized steel. According to the introduction, the coating The service life of the steel plate is 50% longer than that of the galvanized steel plate.
