Galvanized Steel Coil
Galvanized steel coil is a zinc-coated flat steel product manufactured through hot-dip or electrochemical processes to provide sacrificial corrosion protection for the base metal.
Material
Zinc-coated Carbon Steel. Base steel types include Commercial Quality (CQ), Drawing Quality (DQ), Structural Grade (S), and High Strength Low Alloy (HSLA).
Model
GI Coil (Hot-Dip), GA Coil (Galvannealed), EG Coil (Electrogalvanized)
Size
Standard widths range from 600 mm to 2000 mm, with precision slitting capabilities available.
Thickness
0.25 mm to 6.0 mm (including base metal and coating).
Standard
ASTM A653/A653M (GI, GA), ASTM A792/A792M (Galvalume), ASTM A879/A879M (EG); EN 10346 (DX51D-Z, DX52D-Z, etc.); JIS G3302 (SGCC), JIS G3313 (EG).
MOQ
20 Metric Tons.
Delivery Time
Standard lead time is 4 to 8 weeks from order confirmation, depending on coating type and specification.
Long Description
Galvanized steel coil is produced by applying a protective zinc coating to cold rolled or hot rolled steel substrate through either continuous hot-dip galvanizing or electrogalvanizing. In the hot-dip process, the steel strip passes through a molten zinc bath, forming a metallurgically bonded coating that typically consists of a zinc-iron alloy layer and a pure zinc outer layer. The electrogalvanizing process uses an electrical current to deposit a thinner, more uniform zinc layer from an electrolyte solution. This product form is engineered specifically for extended service life in corrosive environments, with the zinc acting as a sacrificial anode to protect the underlying steel from rust. Coating weight, surface treatment, and mechanical properties can be precisely controlled to meet diverse application requirements across multiple industries.
Key Product Highlights
Galvanized coil provides long-term corrosion protection through the sacrificial nature of the zinc coating.
The product is available with various coating types including pure zinc (GI), zinc-iron alloy (GA), and electrodeposited zinc (EG).
Different surface finishes such as regular spangle, minimal spangle, or smooth are offered to meet aesthetic and painting needs.
The base metal can be supplied in a range of strength grades from mild steel to high-strength low-alloy (HSLA).
This coil form is suitable for direct fabrication or further processing like painting (pre-painted galvanized).
Product Advantages
The continuous galvanizing process ensures consistent coating thickness and adhesion across the entire coil length.
Zinc coating provides durable protection that withstands mechanical deformation during forming and fabrication.
Standardized coating designation systems (e.g., Z60, Z275) allow precise specification matching for project requirements.
Material can be supplied with additional chemical treatments (passivation, phosphate) for enhanced paint adhesion and storage.
Full certification includes both base metal mechanical properties and coating quality test results.
Industry Application
This coil is used for manufacturing roofing and wall cladding, automotive structural components, HVAC ducting, electrical enclosures, home appliances, storage tanks, and general fabricated metal products exposed to weather.
Technical Specifications
| Parameter | Unit | Hot-Dip Galvanized (GI) | Electrogalvanized (EG) | Notes |
|---|---|---|---|---|
| Carbon Content (C) | % | ≤ 0.15 (CQ) | ≤ 0.12 (CQ) | Base steel composition varies by quality grade. |
| Manganese (Mn) | % | ≤ 0.60 (CQ) | ≤ 0.50 (CQ) | Base steel composition. |
| Phosphorus (P) | % | ≤ 0.035 | ≤ 0.030 | Typical maximum for forming grades. |
| Sulfur (S) | % | ≤ 0.035 | ≤ 0.030 | Typical maximum for forming grades. |
| Tensile Strength | MPa | 270 – 550 | 270 – 410 | Depends on base steel grade and temper. |
| Yield Strength | MPa | 140 – 550 | 180 – 350 | Depends on base steel grade and temper. |
| Elongation | % | 22 – 40 | 30 – 42 | Minimum values for commercial quality grades. |
| Hardness | HRB | 40 – 85 | 45 – 75 | Rockwell B scale; depends on base steel. |
| Thickness | mm | 0.25 – 6.0 | 0.25 – 3.0 | Includes base metal thickness. |
| Width | mm | 600 – 2000 | 600 – 1650 | Standard production range. |
| Coil Weight | MT | 5 – 25 | 4 – 20 | Typical export coil weight. |
| Surface Treatment | – | Chromate, Phosphate, Oiled | Chromate, Phosphate, Oiled | Chemical treatment for corrosion resistance and paint adhesion. |
| Coating / Finish | – | Zinc (Regular/Minimal Spangle), Galvannealed | Smooth Zinc Coating | GI has visible spangle; GA is matte gray for painting. |
| Rolling Type | – | N/A | N/A | This parameter defines base metal production, not coating process. |
| Standard Example | – | ASTM A653 G90 | ASTM A879 Class 1 | Representative coating designation examples. |
Packaging & Surface Treatment
Coils are carefully packaged to prevent coating damage during handling and transit. Standard packaging includes winding on a steel or cardboard core, wrapping with VCI (Vapor Corrosion Inhibitor) paper and plastic film, and securing on wooden or steel skids with edge protectors and steel strapping. Surface treatments include chromate passivation (clear or blue-yellow), phosphate coating for enhanced paint adhesion, and application of a light protective oil, often specified as regular oiled or dry (minimal oil).
Aliases Names
GI Coil, Galvanized Iron Coil, Zinc Coated Coil, HDG Coil, Galvannealed Coil, Electrogalvanized Coil.
