The main factors affecting the coating thickness of the zinc steel grating are: the metal composition of the steel grating, the surface roughness of the steel grating, the content and distribution of active elements silicon and phosphorus in the steel grating, the internal stress of the steel grating, the steel Grid workpiece geometry.
The current international and Chinese hot-dip galvanizing standards for steel grating hot-dip galvanizing process are divided into sections according to the thickness of the plate. The flat thickness and local thickness of the zinc coating should reach the corresponding thickness to determine the corrosion resistance of the zinc coating.
For steel grating workpieces with different thicknesses, the time required to achieve thermal equilibrium and zinc-iron exchange equilibrium is different, and the thickness of the formed coating is also different. The average thickness of the coating in the standard is based on the industrial production experience value of the above-mentioned galvanizing mechanism, and the local thickness is the empirical value required to take into account the unevenness of the thickness distribution of the zinc coating and the requirements for the corrosion resistance of the coating. Therefore, the ISO standard, the American ASTM standard, the Japanese JIS standard and the Chinese standard have slightly different requirements on the thickness of zinc coating, which are similar.
According to the provisions of the People's Republic of China hot-dip galvanizing standard GB/B 13912-2002. The zinc content standard for hot-dip galvanized steel grating products is the following data: if the thickness of the hot-dip galvanized steel grating is greater than or equal to 6mm, the average thickness of zinc on the hot-dip galvanized steel grating should be greater than 85 microns, and the local thickness should be greater than 70 microns. If the thickness of the hot-dip galvanized steel grating is less than 6mm and greater than 3mm, the average thickness of zinc on the hot-dip galvanized steel grating should be greater than 70 microns, and the local thickness should be greater than 55 microns. If the thickness of the hot-dip galvanized steel grating is less than 3mm and greater than 1.5mm, the average thickness of zinc on the hot-dip galvanized steel grating should be greater than 55 microns, and local should be greater than 45 microns.
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