Carbon Steel GI Sheet — Factory Direct Supplier | Huaxia-Steel
Carbon steel GI sheet, also known as galvanized iron sheet or zinc-coated steel sheet, is hot-dip or electro-galvanized carbon steel used for roofing, cladding, ducting, electrical enclosures, appliances and general fabrication. The zinc coating provides corrosion protection at a lower cost than stainless steel or aluminum. Huaxia Steel supplies GI sheet from Chinese mills in commercial, lock-forming, drawing and structural qualities to JIS, ASTM and EN standards.
Product Overview
GI sheet starts as a cold-rolled or hot-rolled carbon steel substrate. It is then cleaned, annealed and passed through a molten zinc bath or electrolytic zinc bath. Hot-dip galvanizing (HDG) produces a thicker, more durable zinc layer suitable for outdoor and structural use. Electro-galvanizing produces a thinner, smoother coating ideal for painting, deep drawing and precision parts.
Typical Specifications
| Parameter | Range / Value |
|---|---|
| Standard | JIS G3302, ASTM A653/A653M, EN 10346, GB/T 2518 |
| Thickness | 0.12 mm – 6.0 mm |
| Width | 600 mm – 1,500 mm |
| Length | 1,000 mm – 6,000 mm (sheets or coils) |
| Zinc coating | Z40 – Z600 (40 – 600 g/m² total both sides) |
| Surface finish | Regular spangle, minimized spangle, zero spangle, skin-passed |
| Substrate grades | SGCC, DX51D, CS type A/B/C, SS33/SS37/SS40/SS50 |
| Oiling | Dry or oiled (corrosion protection in transit) |
Common Grades and Uses
| Grade | Standard | Typical use |
|---|---|---|
| SGCC | JIS G3302 | General forming, roofing, cladding |
| DX51D | EN 10346 | Lock forming, bending, light drawing |
| CS Type C | ASTM A653 | Commercial quality, general purpose |
| SS40 / SS50 | ASTM A653 | Structural panels, purlins, decks |
| SGLCC | JIS G3321 | Aluzinc / galvalume sheet (55% Al-Zn) |
Zinc Coating Designations
The coating mass is normally expressed as the total zinc weight on both surfaces in grams per square metre. A Z120 coating means 120 g/m² total on both sides. Heavier coatings give longer corrosion life but reduce weldability and formability. Common choices are Z80–Z120 for indoor panels, Z120–Z180 for outdoor cladding in moderate climates, and Z275–Z600 for aggressive industrial or marine environments.
Mechanical Properties (Typical DX51D)
| Property | Value |
|---|---|
| Yield strength | ≥ 140 MPa |
| Tensile strength | 270 – 420 MPa |
| Elongation | ≥ 22% |
| Coating adhesion | No peeling in 180° bend test |
Applications
- Roofing and wall cladding for warehouses, factories and farms
- HVAC ductwork, air handling units and ventilation systems
- Electrical cabinets, switchgear panels and enclosures
- Home appliances: refrigerators, washing machines, ovens
- Automotive body panels and structural brackets
- Corrugated roofing sheets and sandwich panel facings
- General fabrication, signs, lockers and shelving
Quality Assurance
Each coil or bundle is supplied with a mill test certificate showing substrate grade, coating mass, mechanical properties, dimensional tolerance and chemical composition. We can arrange third-party inspection and coating-thickness verification on request. Flatness, surface quality and edge condition are checked before shipment.
Packaging and Shipping
GI sheet is supplied in coils or cut-to-length sheets. Coils are wrapped with anti-rust paper and plastic film, then secured with steel bands. Sheets are bundled with wooden separators and steel strapping. Export packaging can include edge protectors, moisture barriers and fumigation treatment. Standard sea freight is used for full-container loads; LCL and break-bulk options are available.
Why Buy Carbon Steel GI Sheet from Huaxia Steel
- Direct supply from major Chinese galvanized steel mills
- Zinc coating range Z40 to Z600 in regular, minimized or zero spangle
- Cut-to-length, slitting and profiling services available
- Full documentation: MTC, SGS/BV inspection, certificate of origin
- Competitive export pricing for containers and bulk shipments
Request a Quote
Send us your required thickness, width, zinc coating, grade and quantity. We will confirm stock availability, mill lead time and the best shipping option. Contact Huaxia Steel for carbon steel GI sheet pricing today.
Manufacturing Process
GI sheet production begins with a cold-rolled carbon steel coil. The coil is annealed, then passed through a molten zinc bath for hot-dip galvanizing or an electrolytic cell for electro-galvanizing. After coating, the sheet is cooled, passivated, oiled and recoiled or cut to length. Skin passing improves surface flatness and controls spangle size.
- Cold-rolled substrate preparation
- Continuous annealing
- Hot-dip or electrolytic zinc coating
- Air knife coating thickness control
- Passivation and oiling
- Skin passing and tension leveling
- Cutting to sheet or recoiling
Inspection and Testing
Quality checks include coating mass measurement by X-ray fluorescence, coating adhesion by bend test, surface roughness and gloss, dimensional tolerance and mechanical properties. Salt spray testing can be arranged to verify corrosion resistance for specific applications.
Equivalent Standards
| Standard | Grade equivalents |
|---|---|
| JIS G3302 | SGCC, SGCH, SGC340, SGC400, SGC440 |
| EN 10346 | DX51D, DX52D, DX53D, S220GD, S250GD |
| ASTM A653 | CS Type A/B/C, SS33/37/40/50/80 |
| GB/T 2518 | DC51D, DC52D, DC53D |
FAQ
How long does GI sheet last outdoors?
Lifespan depends on the environment. In rural or dry climates, Z120 coating can last 10 – 20 years. In industrial or marine environments, Z275 or heavier coatings are recommended for similar life.
Can GI sheet be painted?
Yes. Proper surface preparation and a compatible primer are essential. Zero-spangle or skin-passed GI sheet provides the best paint adhesion.
What is the difference between GI and GL sheet?
GI is zinc-coated. GL (galvalume) is 55% aluminum-zinc coated, offering better corrosion resistance and heat reflectivity. GL is often used for roofing in hot climates.
