Z180 Z275 Galvanized Coil

Mainly include: shedding, scratches, passivation spots, zinc particles, thick edges, air knife streaks, air knife scratches, exposed steel, inclusions, mechanical damage, poor performance of the steel base, wavy edges, buckling, size incompatibility, Embossing, inconsistent zinc layer thickness, roll printing, etc.

The main reasons for the zinc layer to fall off are: surface oxidation, silicon compounds, too dirty cold rolled emulsion, too high oxidizing atmosphere and protective gas dew point in the NOF section, unreasonable air-fuel ratio, low hydrogen flow, oxygen infiltration in the furnace, strip steel The temperature of entering the pot is low, the furnace pressure in the RWP section is low, and the furnace door suction, the furnace temperature in the NOF section is low, the grease does not evaporate, the aluminum content of the zinc pot is low, the unit speed is too fast, the reduction is insufficient, and the zinc liquid stays The time is too short and the coating is too thick.

The causes of white rust and black spots are as follows: black spots are formed by further oxidation of white rust.