Galvanized Steel Coil Factory knowledge of galvanized sheet coil

A-What are the two types of hot-dip galvanizing according to the different annealing methods?

Answer: It can be divided into two types: in-line annealing and off-line annealing, which are also called protective gas method and flux method respectively.

B-What are the commonly used steel grades for hot-dip galvanized sheets?
Answer: Product categories: general commodity coil (CQ), galvanized sheet for structural use (HSLA), deep-drawn hot-dip galvanized sheet (DDQ), bake-hardening hot-dip galvanized sheet (BH), dual-phase steel (DP), TRIP steel (transformation induced plasticity steel), etc.

C- What types of galvanizing annealing furnaces are there?
Answer: There are three types of vertical annealing furnaces, horizontal annealing furnaces and vertical and horizontal annealing furnaces.

D-What are the cooling methods of cooling towers?
A: There are two kinds: air cooling and water cooling.

E-What are the main defects of hot-dip galvanizing?
Answer: Mainly include: falling off, scratches, passivation spots, zinc particles, thick edges, air knife streaks, air knife scratches, exposed steel, inclusions, mechanical damage, poor performance of steel base, wave edges, buckling, dimensions Mismatch, embossing, misalignment of zinc layer thickness, roll printing, etc.

F-Known: the production specification is 0.75×1050mm, and the coil weight is 5 tons. What is the length of the coil? (The specific gravity of the galvanized sheet is 7.85g/cm3)

Solution: L=G/(h×b×p)=(5×1000)/(0.785×1.050×7.5)=808.816m

Answer: The coil is 808.816m long.

G- What are the main reasons for the zinc layer to fall off?
Answer: The main reasons for the peeling of the zinc layer are: surface oxidation, silicon compounds, too dirty cold-rolled emulsion, too high oxidizing atmosphere and protective gas dew point in NOF section, unreasonable air-fuel ratio, low hydrogen flow rate, and oxygen infiltration in the furnace. The temperature of the strip steel 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 is not evaporated, the aluminum content of the zinc pot is low, the unit speed is too fast, the reduction is insufficient, and the zinc liquid The residence time is too short and the coating is too thick.