What is HDG Hot Dip Galvanized Steel Coil?
Hot Dip Galvanized Steel Coil is a rust-proof steel that is made by dipping the steel into molten zinc (about 450°C) to form a zinc-iron alloy layer.
Compared with other galvanizing processes
Characteristics | Hot-dip galvanizing (GI) | Electroplating zinc (EG) | Alloy zinc plating (GA) |
Coating thickness | 50-150μm | 3-20μm | 10-50μm |
Corrosion resistance | ★★★★★ (preferred for outdoor use) | ★★★☆ (for indoor use) | ★★★★☆ (for automobiles) |
What is the difference between HDG and zinc plating?
The core difference between HDG (hot-dip galvanizing) and ordinary zinc coating (such as electroplating) lies in the process, coating structure and performance
Process Differences
Characteristics | HDG (hot dip galvanizing) | Ordinary zinc coating (such as electroplating zinc) |
Processing method | Steel immersed in molten zinc at 450°C | Electrolytic deposition (room temperature) |
Coating formation | Zinc-iron alloy layer (Γ/δ phase) + pure zinc layer | Pure zinc layer (no alloy layer) |
Coating thickness | 20-200μm (thick, suitable for outdoor use) | 3-20μm (thin, suitable for indoor use) |
Adhesion | Extremely strong (metallurgical bond) | Weak (physical adhesion) |
Zinc layer weight and corrosion resistance of Galvanized Steel Coil-Gl
Zinc layer code | Zinc layer weight (g/m²) | Average thickness (μm) | Applicable environment |
Z60 | 60 | 8.5 | Dry indoor environment (such as furniture, cabinets) |
Z120 | 120 | 17 | Ordinary outdoor (such as building fences) |
Z180 | 180 | 25 | High humidity/industrial areas (such as chemical plant pipelines) |
Z275 | 275 | 39 | Harsh environment (coastal, salt spray areas) |
Which is better electro galvanized or hot dipped galvanized?
Electrogalvanizing deposits a uniform zinc layer (pure zinc or zinc alloy) on the surface of the steel plate through electrolytic reaction. The coating thickness is usually 5~20μm, which is suitable for high-precision stamping and bending (such as automotive panels, electronic components), but attention should be paid to zinc layer burning during welding (easy to produce pores); hot-dip galvanizing immerses the steel plate in molten zinc liquid to form a coating composed of a zinc-iron alloy layer (inner layer) and a pure zinc layer (outer layer). The thickness is generally 60~120μm, and can even reach more than 200μm. It is suitable for structural parts and large steel products (such as angle steel and channel steel), and has good weldability (the zinc layer is thicker and can withstand high temperatures)
What are hot dip galvanized coils used for?
Hot Dipped Galvanized Gl Steel Coil are used for
Roof steel plates, wall color-coated plates, light steel keels, etc. in the construction field. The corrosion resistance of the zinc layer can resist environmental erosion such as acid rain and humidity, and extend the life of outdoor components;
Household appliance shells, refrigerators, air conditioners, washing machines, etc. Shell substrates;
Automotive parts body frames, chassis structural parts, fuel tank brackets, etc., use the cathodic protection of the zinc layer to prevent body corrosion
Pipelines and containers: water and gas pipelines and the inner layer of storage tanks to prevent medium corrosion (such as fire pipelines, chemical storage tanks)
Traffic equipment: highway guardrails, railway carriage floors, container plates, etc., suitable for outdoor wind and rain and mechanical wear scenes.
