Defects mainly include: falling off, scratches, passivation spots, zinc particles, thick edges, air knife stripes, air knife scratches, exposed steel, inclusions, mechanical damage, poor performance of steel base, wavy edges, ladles, improper size, embossing, improper thickness of zinc layer, roller printing, etc.
The main reasons for zinc layer falling off are: surface oxidation, silicon compounds, too dirty cold rolling emulsion, too high oxidation atmosphere in NOF section and dew point of protective gas, unreasonable air-fuel ratio, low hydrogen flow, oxygen infiltration in the furnace, low temperature of strip steel entering the pot, low furnace pressure in RWP section and air suction in furnace door, low furnace temperature in NOF section, endless oil evaporation, low aluminum content in zinc pot, too fast unit speed, insufficient reduction, too short residence time in zinc liquid The coating is too thick.
