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1、What is the main use of hot-dip galvanized sheet?

A: Hot-dip galvanized sheet is mainly used in construction, home appliances, automobiles, machinery, electronics, light industry and other industries.

2、What types of galvanizing methods are available in the world?

A: There are three types of galvanizing methods, such as electro-galvanizing, hot-dip galvanizing and galvanizing coating.

3、Hot dip galvanizing can be divided into which two types according to the different annealing methods?

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

4、What are the common steel grades for hot-dip galvanized sheet?

A: Product categories:: general commercial coil (CQ), structural galvanized sheet (HSLA), deep-drawn hot-drawn galvanized sheet (DDQ), bake-hardened hot-drawn galvanized sheet (BH), dual-phase steel (DP), TRIP steel (phase-change-induced plasticity steel) and so on.

5, galvanized annealing furnace has which forms?

A: There are vertical annealing furnace, horizontal annealing furnace and vertical and horizontal annealing furnace three.

6, usually cooling tower cooling methods are several?

A: There are two kinds: air-cooled and water-cooled.

7, hot dip galvanizing defects are mainly?

A: Mainly: 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, wave edges, ladybird curves, the size does not fit, embossing, zinc layer thickness does not fit, roller marks and so on.

8, known: production specifications for the 0.75 × 1050mm, volume weight of 5 tons, ask the length of the coil of steel strip? (The specific gravity of galvanized sheet is 7.85g/cm3)

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

A: The coil of strip is 808.816m long.

9, what are the main reasons for the zinc layer off?

A: The main reasons for zinc layer shedding are: surface oxidation, silicon compounds, cold tie emulsion is too dirty, NOF section of the oxidizing atmosphere and protective gas dew point is too high, the air-fuel ratio is unreasonable, the hydrogen flow rate is low, there is oxygen infiltration into the furnace, the strip into the pot at a low temperature, the RWP section of the furnace pressure is low and the furnace door suction, the NOF section of the furnace temperature is low, the evaporation of oil and grease is not exhaustive, the zinc pot of aluminum is low, the unit is too fast, the reduction is not adequate The time of stay in zinc liquid is too short and the plating layer is too thick.

10、What are the reasons for white rust and black spot?

A: Black spot is formed by further oxidation of white rust. The main reasons for white rust are:

Poor passivation, passivation film thickness is not enough or uneven; the surface is not oiled or residual moisture on the surface of the strip; the strip surface contains moisture when rolled; passivation is not completely dried; moisture or rain in transportation or storage; finished product storage time is too long; galvanized sheet contact with other acids and alkalis, and other corrosive mediums or stored together.

11、How long is the maximum storage time allowed for finished products in the warehouse? Why?

A: It is allowed to be stored for three months in order to avoid oxidization caused by too long storage.

12、What is the length tolerance of galvanized steel?

A: The length tolerance is not allowed to have a negative value, the maximum is not allowed to exceed +6mm.

13、What is a large zinc flower? What is a small zinc flower?

A: Large zinc flower is the normal zinc flower, according to the normal production process can produce large zinc flower, its crystalline nucleus diameter of not less than 0.2mm; crystalline nucleus diameter of less than 0.2mm known as small zinc flower, this zinc flower can not be identified with the naked eye.

14, hot-dip galvanized layer of the protection principle?

A: Because zinc in a corrosive environment can be formed on the surface of the corrosion resistance of a good film. It not only protects the zinc layer itself, but also protects the steel base.

15, hot-dip galvanized sheet passivation principle?

A: chromate passivation of galvanized sheet can form a passivation film, the chemical reaction formula is as follows: Zn + H2GrO4-ZnGrO2 = H2

Solution passivation family of trivalent chromium is insoluble in water, chemically inactive, playing the role of the skeleton, while the hexavalent chromium in it is soluble in water, can play a role in the passivation of the film scratches again passivation, passivation of the film with the role of healing. Therefore, within certain limits, the passivation film can prevent steam or humid air directly erode the galvanized sheet, dun zinc layer plays a protective role.

16, test the corrosion resistance of hot-dip galvanized sheet of which methods?

A: test the corrosion resistance of hot-dip galvanized sheet has three methods: salt spray test; moisture test; erosion test.

17, hot-dip galvanized products, why the rust treatment?

A: When the hot-dip galvanized sheet in the humid air, especially when the air contains SiO2, CO2, NO2 and NO and other acidic substances, the surface of the galvanized layer will soon generate loose white rust. The main components of white rust are ZnO and Zn(OH)2. This kind of white rust not only affects the aesthetics, but also brings great difficulties to the future use.

18. Reasons for white rust