Galvanized coil, dipping a sheet of steel into a molten zinc bath so that it adheres to a sheet of zinc on its surface. At present, the continuous galvanizing process is mainly used for production, that is, the steel plate into a roll of continuous immersion in the melting of zinc plating tank made of galvanized steel plate;

Definition of galvanized coil coating

1, normal zinc flower coating

Galvanized coil zinc layer in the normal solidification process, zinc grains grow freely formed with obvious zinc flower morphology of the coating.

2, small zinc flower coating

During the solidification process of zinc layer, zinc grains are artificially restricted to form as fine zinc flower coating as possible.

3. Zinc free flower coating

By adjusting the chemical composition of the bath, the coating has no visible zinc flower morphology and uniform surface.

4, zinc iron alloy coating

Heat treatment of the steel strip through the zinc bath, so that the whole coating zinc and iron alloy layer, the appearance of the coating is dark gray, no metallic luster, in the process of violent molding is easy to powder, suitable for in addition to general cleaning, without further treatment can be directly painted coating.

5, the thickness of the coating

For both sides of galvanized steel sheet, different zinc layer weight coating is required.

6, finishing

Finishing is a cold rolling process of galvanized steel with a small amount of deformation for one or more of the following purposes. Improve the surface appearance of galvanized steel plate or suitable for decorative coating; So that the finished products do not see the processing of the phenomenon of slip line or fold temporarily reduced to the minimum.

What is the use of galvanized coils

Galvanized coil is a thin sheet of steel dipped into a molten zinc tank, so that the surface of the sheet is attached to a layer of zinc. Galvanized coil can be divided into hot rolled galvanized sheet coil and cold rolled hot galvanized sheet coil, the current main use of continuous galvanized process production, that is, into a coil of steel plate continuous dip in the melting of zinc plating tank made of galvanized steel plate.

Because galvanized coil has strong corrosion resistance, good surface quality, conducive to deep processing, economic and practical characteristics, so it is widely used in construction, household appliances, automobiles, containers, transportation and household industries and other fields. Especially steel structure construction, automobile manufacturing, steel warehouse manufacturing and other industries.

Defects in galvanized coils

Galvanized roll is easy to fall off, scratch, passivation spot, zinc grain, thick edge, air knife striation, air knife scratch, exposed steel, inclusion, mechanical damage, poor performance of steel base, wave edge, ladle, size, imprint, zinc layer thickness, roll printing and other defects.

The main reasons for the shedding of zinc layer of galvanized coil are surface oxidation, silicon compound, dirty cold tie emulsion, too high dew point of oxidizing atmosphere and protective gas in NOF section, unreasonable air-fuel ratio, low hydrogen flow, low oxygen infiltration in furnace, low temperature of strip into pot, low furnace pressure in RWP section and air suction in furnace door, low furnace temperature in NOF section. Oil evaporation is not enough, zinc pot aluminum content is low, the unit speed is too fast, insufficient reduction, zinc liquid residence time is too short, thick coating.