The grades of hot galvanizing products vary according to the different of the hot standards of the steel mills. But there are corresponding grades between grades and grades. Hot galvanizing products grades will vary with the steel and mechanical properties of the steel sheet.
Therefore, CAMELSTEEL suggests that purchaser should also change the selection according to different usage function at the time of purchase. The most used standards and grades in domestic are as follows:
Japanese standard: SGCC，CGCC
American standard: ATSM A 153-03
German standard: DX51D, DX52D, DX53D, DX54D, DX55D
B. Surface treatment.
1. Passivation treatment.
The passivation treatment is the last step in chemical cleaning. After cleaning and phosphating, the metal surface of galvanized steel sheet is very clean and activated. And it’s also susceptible to be corroded. Therefore, it must be immediately do the passivation treatment, so that generate protective film on the metal surface after cleaning, and also slow down the corrosion.
The process of forming a trivalent or hexavalent chromium layer on its surface with chromate solution and metal is called passivation, also known as chromizing. But passivation is rarely used alone, often supporting the use of phosphating to close the pores of the phosphating layer, and make the bare steel in the phosphating layer passivating. It can also inhibit the corrosion effect of residual phosphating accelerator.
2. Oil treatment.
It is a way to apply grease that in order to make galvanized steel plate won’t be corroded by the outside air, rain and other erosion in the storage and transportation process, resulting the corrosion and oxidation in the surface of hot-dip galvanized steel sheet, to achieve a better protection of the steel surface. Oil treatment is divided into fat liquoring and light oil.
3. The varieties of zinc spangle.
The zinc spangle of hot galvanizing steel sheet can be divided into big spangle, regular spangle, small spangle and zero spangle.