Hot-dip galvanizing is a process where molten metal reacts with the iron substrate to form an alloy layer, thus combining the substrate and the coating. In the process of hot-dip galvanizing, steel parts are first pickled to remove the surface iron oxide. After pickling, they are cleaned in a solution of ammonium chloride or zinc chloride or a mixed solution of ammonium chloride and zinc chloride, and then sent to the hot-dip galvanizing bath. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
Hot-dip galvanizing is one of the effective means to delay the environmental corrosion of steel materials. It involves immersing steel products that have been cleaned and activated on the surface into molten zinc liquid, where a well-adhering zinc alloy coating is formed on the surface of the steel products through the reaction and diffusion between iron and zinc. Compared with other metal protection methods, the hot-dip galvanizing process has advantages in the combined protective characteristics of the physical barrier and electrochemical protection of the coating, the bonding strength between the coating and the substrate, the density, durability, maintenance-free nature, economy of the coating, and its adaptability to the shape and size of the products. Currently, hot-dip galvanized products mainly include steel plates, steel strips, steel wires, steel pipes, etc., among which hot-dip galvanized steel plates account for a large proportion.
The production process of hot-dip galvanizing is as follows:
Base material → Degreasing → Water washing → Pickling → Water washing → Rinsing → Flux solution → Drying → Hot-dip galvanizing → Cooling → Inspection → Packaging
Application scope
For a long time, hot-dip galvanizing technology has been favored by people due to its low coating cost, excellent protective properties and attractive appearance. It is widely used in fields such as automobiles, construction, household appliances, chemicals, machinery, petroleum, metallurgy, light industry, transportation, power, aviation and marine engineering.
Product Parameter
| product name | Hot-dip galvanized coil |
| Thickness | 0.12mm-3.5mm |
| Width | 600mm-1500mm |
| Length | 508mm/610mm，Customizable |
| Standard | AISI,ASTM,DIN,JIS,GB,JIS,SUS,EN |
| · zinc coating | Hot-dip galvanizing：60-275g/m² |
| Hot-dip galvanizing：80-275g/m² |
Galvanized Surface Selection
| Zero Spangle | Galvanized Spangle | Normal spangle | Large Zinc Flower |
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| service environment | Recommended zinc coating thickness |
| Indoor use | Z10 or Z12 (100g/㎡or 120g/㎡) |
| Suburbs | Z20 and painted (200g/㎡) |
| City or industrial area | Z27（270g/㎡) or G90（American Standard）and painted |
| Coastal areas | Thicker than the Z27 (270g/m²) or G90 (American standard）and painted |
| Stamping or Deep Drawing Application | Thinner than the Z27 (270 g/m²) or G90 (US standard) to prevent coating peeling after stamping |
| Surface treatment type | Code | Feature |
| Chromic acid treatment | C | Excellent corrosion resistance |
| chromic acid treatment + oil coating | S | Good corrosion resistance |
| Phosphoric acid treatment (including pore sealing treatment) | P | Demonstrates certain corrosion resistance with excellent paint performance |
| Phosphoric acid treatment (including pore sealing treatment) + oil coating | Q | Possesses certain corrosion resistance and exhibits excellent paint performance, preventing rust formation during transportation and storage. |
| Phosphoric acid treatment (excluding sealing treatment) | T | Demonstrates certain corrosion resistance with excellent paint performance |
| Phosphoric acid treatment (excluding sealing treatment) + oil coating | V | Possesses certain corrosion resistance, exhibits excellent paint performance, and prevents rust formation |
| Oiling | O | Prevent rusting during transportation and storage |
| No treatment | M | Ideal for immediate painting |