Mainly problems in the production process of galvanized steel plate
are shedding, scratches, passivation spots, zinc particles, thick side, air knife streaks, air knife scratches, exposed steel, inclusions, mechanical damage, steel-based poor performance, wave edge, embossing, zinc layer thickness and so on.
Main reasons of zinc layer off are: the surface oxidation, silicon compounds, cold emulsion emulsion, high pointed NOF oxidation atmosphere and protective gas, unreasonable air-fuel ratio, low hydrogen flow, furnace oxygen infiltration, low woking temperature, RWP section furnace pressure is low and the furnace suction, low NOF furnace temperature, the unit speed is too fast, the reduction is not enough, zinc solution staying time is too short, the coating is thicker.
The main reasons of white rust are:
1. When the strip surface contains water
2. The surface is not coated or the surface residual moisture
3. Galvanized steel plates are stored together with acid and corrosive media.
4. Galvanized steel plates are not completely dried during passivation
5. Passive film thickness is not enough or uneven
6. Galvanized steel plates get damp during transportation or storage