1.How long can the finished galvanized coil be stored in the warehouse? Why?
A: It is allowed to be stored for three months to avoid oxidation caused by storage for too long.
2. What is the length tolerance of galvanized steel sheet?
Answer: The length tolerance is not allowed to have a negative value, and the maximum is not allowed to exceed +6mm.
3. What is Zinc Flower spangle? What is a small spangle?Zero spangle?
Answer: The big spangle is the normal spangle. According to the normal production process, the large spangle can be produced. The diameter of the crystal nucleus is not less than 0.2mm; the diameter of the crystal nucleus is less than 0.2mm, which is called the small spangle. Visually identifiable.
4. What is the protection principle of hot-dip galvanized layer?
Answer: Because zinc can form a film with good corrosion resistance on the surface in a corrosive environment. It protects not only the zinc layer itself, but also the steel base.
5. What is the principle of passivation of hot-dip galvanized coil?
Answer: The chromate passivation treatment of galvanized sheet can form a passivation film, and its chemical reaction formula is as follows: Zn+H2GrO4-ZnGrO2=H2
The trivalent chromium in the solution passivation family is insoluble in water, chemically inactive, and acts as a skeleton, while the hexavalent chromium is easily soluble in water and can play a role in re-passivation when the passivation film is scratched. It has the healing effect of passivation film. Therefore, within a certain limit, the passivation film can prevent the direct erosion of the galvanized sheet by steam or humid air, and the zinc layer plays a protective role.
6. What are the methods for testing the corrosion resistance of hot-dip galvanized sheet coil?
Answer: There are three methods to test the corrosion resistance of hot-dip galvanized sheet: salt spray test; humidity test; erosion test.
7. Why should anti-rust treatment be carried out on hot-dip galvanized products?
Answer: When the hot-dip galvanized sheet is in humid air, especially when the air contains acidic substances such as SiO2, CO2, NO2 and NO, the surface of the galvanized layer will soon form loose white rust. The main components of white rust are ZnO and Zn(OH) 2. This kind of white rust not only affects the appearance, but also brings great difficulties to future use.
8. What are the causes of white rust on galvanized coil?
Answer: The reasons for white rust are: hot-dip galvanizing is placed together with other corrosive media such as acid, alkali and salt; the passivation film or anti-film is damaged; the passivation or oiling effect is not good; the storage warehouse is not well ventilated, Moisture; galvanized sheet is sprayed with water during transportation; transported at low temperature and stored at high temperature, forming condensation.
Post time: May-10-2022