Galvanized Sheet-Process Flow
 
Production process
A, cold and hot rolled steel plate by alkaline degreasing, and water washing, drying and then into the radiation tube heating horizontal (vertical) furnace for annealing, furnace into a certain amount of hydrogen to create a reducing atmosphere;
B, heated to a certain temperature of the steel strip under certain conditions immersed in zinc hot dip galvanizing. After the strip steel immersed in the zinc liquid comes out of the zinc pot, the amount of galvanizing is controlled by an air knife;
C, zinc flower size by the composition of liquid zinc to control at the same time, the use of forced cooling method to control, small zinc flower products in the zinc flower began to spread before, with small zinc flower equipment for quenching to prevent zinc liquid to continue to spread, the formation of small zinc flower;
D, after hot galvanizing strip steel cooling through the surface finishing, and finally according to the use, respectively, the surface passivation treatment or direct production into color coated coil.
According to the classification of coating methods:
a. Hot-dip galvanized steel sheet
B. Electro-galvanized steel sheet
Types and Uses of Galvanized Sheet

Product indicators and representation
A, zinc layer adhesion: under normal circumstances Z10, Z12, Z18, said the amount of zinc per square meter is 100 grams, 120 grams, 180 grams;
Application of Galvanized Sheet for Building
A, housing construction roof or processing color coated board
B. Construction site fence
C, thermal pipeline insulation skin
d. Formwork support for buildings and bridges
e. Air-conditioning duct
f. Steel plate warehouse
g. Chimney of rural houses
h. Fume hood
I. advertising board
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Quality Defects and Precautions of Galvanized Sheet
A, galvanized sheet common quality defects
1. Defect name: galvanized stripping
Defect performance: dezincification
Cause: poor furnace temperature, improper substrate handling, etc.
2. Name of defect: ungalvanized
Defect performance: the surface part of the steel plate is not galvanized
Causes: poor raw materials, poor pretreatment degreasing, poor furnace temperature
3. Defect name: zinc flower bad
Defect performance: zinc flower size is not uniform, no zinc flower
Cause: poor heating of furnace area and poor cooling control
4. Defect name: zinc scar
Defect performance: steel plate surface point, granular zinc slag adhesion
Cause: scum or bottom slag in zinc pot adheres to steel strip
5. Defect name: oxidation
Defect performance: produce white rust
Cause: in the process of storage, absorption of moisture in the air, oxidation
2Zn O2 → 2ZnO
5ZnO 2CO2 3H2O →2ZnCO3·3Zn(OH)2
6. Defect Name: Black Spot
Defect performance: black dot, block spots
Cause: impure precipitation reacts with moisture and carbon dioxide in the atmosphere, or friction during transportation.
7. Name of defect: side wave and medium wave
Defect performance: the edge or middle is wavy
Cause: poor raw materials or poor working condition of straightening roller
8. Defect name: jagged edge
Defect performance: the edge is sawtooth shape
Cause of occurrence: the edges are uneven and serrated when the raw materials are cold-bound.
9. Defect name: uneven board surface
Defect Manifestations: Dents
Cause: raw material pits or roller surface foreign matter adhesion
B, galvanized coil transportation and storage should pay attention to matters
1. Choose a ventilated place to store in the house to avoid dew erosion or moisture penetration
2. Confirm that the wrapping paper is not damaged during storage.
Shorten the storage time as much as possible and protect its surface before corrosion.
4. If the plate is subjected to abnormal external pressure, the zinc layer will partially fall off.
5. It is necessary to prevent dirt and oil powder from sticking to the surface, which will affect the galvanizing effect.
6, steel coil below should be added with wood or support frame, stacking layer should not exceed two layers
7, transportation should be covered with rain cloth, and must be used with wood pads and rubber pads, fixed with ropes