Galvanized Steel Sheet (GI Sheet)
Galvanized steel sheet (GI sheet) is hot-dip zinc coated carbon steel offering excellent corrosion protection for 20-50 years. Thickness 0.12-4.0mm, width 600-1500mm, zinc coating Z40-Z600. Multiple substrate grades (DX51D-DX54D, S280GD/S350GD). Mill test certificate provided.
| Material | Carbon Steel with Hot-Dip Zinc Coating |
|---|---|
| Grade / Standard | DX51D+Z / SGCC / S280GD+Z / S350GD+Z |
| Thickness | 0.12mm - 4.0mm |
| Width | 600mm - 1500mm |
| Inner Diameter (ID) | 508mm / 610mm |
| Coil Weight | 3-12 Tons (Max 15 Tons) |
| Delivery Condition | hot_rolled / cold_rolled / annealed |
| Surface Treatment | galvanized / coated |
| MOQ | 5 Tons |
| Delivery Time | 10-25 Days / In Stock |
| Loading Port | Tianjin / Shanghai / Qingdao |
Overview of Galvanized Steel Sheet (GI Sheet)
Galvanized steel sheet, commonly known as GI sheet, is a carbon steel sheet coated with a layer of zinc through the hot-dip galvanizing process to provide excellent corrosion protection in atmospheric, fresh water, and mildly corrosive environments. Specified under JIS G3302 / ASTM A653 / EN 10346 standards, GI sheet has become one of the most widely used coated steel products globally, accounting for over 100 million tons of annual production worldwide. The zinc coating provides both barrier protection and sacrificial cathodic protection, ensuring long-term durability against rust and corrosion.
GI sheet is manufactured through continuous hot-dip galvanizing line (CGL) process where cold rolled steel coil is cleaned, annealed, and immersed in a molten zinc bath at approximately 460°C, then air-cooled with controlled atmosphere. The standard zinc coating weight ranges from Z40 (40 g/m²) to Z600 (600 g/m²) per side, with Z80, Z120, Z180, and Z275 being the most commonly specified weights for general construction, manufacturing, and roofing applications. The grade is the international benchmark for cost-effective corrosion protection in construction roofing, wall cladding, HVAC ductwork, household appliances, automotive components, and a wide range of industrial manufacturing applications.
Key Features and Coating Performance
GI sheet offers superior corrosion resistance compared to bare cold rolled steel through dual protection mechanisms: barrier protection where the zinc layer physically separates steel from corrosive environments, and sacrificial cathodic protection where zinc preferentially corrodes to protect exposed steel at cuts, edges, and scratches. The galvanized coating provides typical service life of 20-50 years in atmospheric exposure depending on coating weight and environmental conditions, with Z275 coating providing 50+ years protection in normal urban environments.
The sheet is supplied in thickness range from 0.12mm to 4.0mm with width from 600mm to 1500mm, in coil form with weight 3-12 tons or cut-to-length sheets in standard sizes (1000×2000mm, 1220×2440mm, 1250×2500mm). Multiple substrate grades are available including DX51D+Z (general forming), DX52D+Z (forming for deep drawing), DX53D+Z (deep drawing), DX54D+Z (extra deep drawing), and S280GD+Z / S350GD+Z (structural high strength). Surface treatments include chromate passivation (Cr3+ environmentally friendly or Cr6+ traditional), oiled (with anti-finger print coating), unoiled, and skin-passed. Spangle options include regular spangle, minimum spangle, and zero spangle for visible architectural applications.
Main Applications of GI Steel Sheet
Galvanized steel sheet is the primary material for construction roofing and wall cladding applications worldwide, including corrugated metal roofing for residential, agricultural, and industrial buildings, IBR roofing profiles, standing seam metal roofs, and architectural wall panels for commercial structures. The construction industry also uses GI sheet for steel framing, light gauge structural members, ceiling tiles, drywall studs, and metal door and window frames where long-term corrosion protection is essential.
The HVAC and ductwork industry employs GI sheet for air conditioning ducts, ventilation systems, exhaust hoods, smoke vents, and industrial ventilation equipment requiring corrosion resistance and easy fabrication. Household appliance manufacturers use GI sheet for refrigerator outer panels, washing machine cabinets, water heater tanks, dishwasher panels, and small appliance housings as raw material for downstream painting or color coating processes. The automotive industry uses GI sheet for body panels, chassis components, fuel tanks, and exhaust system shields. Other major applications include grain storage silos, livestock equipment, garage doors, fence panels, highway guardrails, electrical enclosures, transformer housings, traffic sign substrates, container manufacturing, and as primary substrate for prepainted galvanized (PPGI) and corrugated steel sheet production.
Why Choose Us for Galvanized Steel Sheet
Shandong Tanglu Metal Material Co., Ltd. supplies premium galvanized steel sheet sourced from major Chinese steel mills including Baosteel, HBIS, Shougang, and WISCO with proven international export experience and certified continuous galvanizing line (CGL) production facilities meeting ISO 9001, ISO 14001, ASME, and PED requirements. Every GI sheet undergoes mandatory chemical composition analysis, mechanical property testing including tensile, yield, and elongation verification, zinc coating weight testing per ASTM A90 / EN ISO 1460, salt spray corrosion testing per ASTM B117, surface quality inspection, and dimensional inspection per JIS G3302 / ASTM A653 / EN 10346 latest revision.
We offer comprehensive specification range covering thickness from 0.12mm to 4.0mm and width from 600mm to 1500mm with multiple zinc coating weights (Z40 to Z600), substrate grades (DX51D to DX54D, S280GD/S350GD), surface treatments (chromated, oiled, unoiled), and spangle options (regular, minimum, zero spangle). With monthly supply capacity of 30,000 tons of galvanized products and established export relationships with construction contractors, roofing manufacturers, HVAC companies, appliance OEMs, and PPGI processors in over 80 countries including Africa, Southeast Asia, Middle East, Europe, and South America, we support both small project orders and large bulk container shipments. Each shipment includes original mill test certificate (MTC) conforming to EN 10204 3.1 standard with zinc coating weight verification, with EN 10204 3.2 and third-party inspection (SGS, BV, TUV) available for critical applications.
📐 Dimension & Size Table
| Thickness (mm) | Width (mm) | Zinc Coating (g/m²) | Coil Weight (T) |
|---|---|---|---|
| 0.12 | 600-1250 | Z40-Z120 | 3-5 |
| 0.15 | 600-1250 | Z40-Z180 | 3-5 |
| 0.18 | 600-1250 | Z40-Z180 | 3-6 |
| 0.20 | 600-1250 | Z60-Z180 | 3-6 |
| 0.25 | 600-1500 | Z60-Z275 | 3-8 |
| 0.30 | 600-1500 | Z60-Z275 | 3-8 |
| 0.40 | 700-1500 | Z80-Z275 | 3-8 |
| 0.50 | 700-1500 | Z80-Z275 | 5-10 |
| 0.60 | 700-1500 | Z80-Z275 | 5-10 |
| 0.80 | 700-1500 | Z80-Z275 | 5-10 |
| 1.00 | 700-1500 | Z100-Z275 | 5-12 |
| 1.20 | 700-1500 | Z120-Z275 | 5-12 |
| 1.50 | 800-1500 | Z120-Z275 | 5-12 |
| 2.00 | 1000-1500 | Z180-Z275 | 5-12 |
| 2.50 | 1000-1500 | Z180-Z275 | 5-12 |
| 3.00 | 1000-1500 | Z180-Z275 | 5-15 |
| 4.00 | 1000-1500 | Z180-Z275 | 5-15 |
* Custom sizes available upon request. Tolerances per relevant international standards.
🔬 Chemical Composition
| Element | Min | Max | Display Value | Note |
|---|---|---|---|---|
| C | - | 0.12 | ≤0.12 | DX51D+Z per EN 10346 |
| Si | - | 0.50 | ≤0.50 | |
| Mn | - | 0.60 | ≤0.60 | |
| P | - | 0.10 | ≤0.10 | |
| S | - | 0.045 | ≤0.045 | |
| Ti | - | 0.30 | ≤0.30 | Optional, deep drawing grades |
| Zn (Coating) | 99.00 | - | ≥99.0% Pure Zinc | Hot-dip coating composition |
| Al (in Zn bath) | 0.15 | 0.25 | 0.15-0.25% | Coating bath additive |
* Chemical composition may vary by heat, thickness and specification. Please refer to the actual mill test certificate.
⚙️ Mechanical Properties
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (DX51D+Z) | 270-500 | MPa | Per EN 10346, general forming |
| Yield Strength (DX51D+Z) | ≤500 | MPa | Maximum value |
| Elongation A80 (DX51D+Z) | ≥22 | % | Gauge length 80mm |
| Tensile Strength (DX54D+Z) | 260-350 | MPa | Extra deep drawing grade |
| Elongation A80 (DX54D+Z) | ≥36 | % | Extra deep drawing performance |
| Yield Strength (S280GD+Z) | ≥280 | MPa | Structural high strength grade |
| Tensile Strength (S280GD+Z) | ≥360 | MPa | Structural grade |
| Elongation A80 (S280GD+Z) | ≥18 | % | Structural grade |
| Zinc Coating Adhesion | Pass | - | 180° bend test, no flaking |
| Salt Spray Test | ≥240 | hours | Z275 coating, ASTM B117 to 5% red rust |
* Values shown are minimum requirements unless otherwise stated.
📦 Commercial Information
| Packaging | Standard seaworthy export packing for galvanized steel coils and sheets. Coils wrapped with PE film for moisture protection, then bundled with steel strapping (4-6 wraps per coil), with eye protection rings on inner diameter and weather-resistant outer wrap. Sheets bundled in stacks with wooden pallets (typically 3-5 tons per stack), cardboard or wooden corner protectors, and steel strapping. Each package clearly tagged with heat number, grade designation (DX51D+Z, S280GD+Z, etc.), thickness, width, zinc coating weight (Z80, Z180, Z275), spangle type (regular/minimum/zero), and surface treatment (chromated/oiled). Custom packaging including individual sheet protection film and waterproof shrink wrapping available for premium architectural applications. |
|---|---|
| Payment Terms | T/T (Telegraphic Transfer),L/C (Letter of Credit),D/P (Documents against Payment),Western Union,PayPal |
| Price Term | FOB,CFR,CIF,EXW |
| Supply Capacity | 30,000 Tons/Month (Galvanized Products) |
| Loading Port | Tianjin / Shanghai / Qingdao |
Why Choose Our Galvanized Steel Sheet (GI Sheet)?
Mill Certified Premium Quality
GI sheet supplied with original mill test certificate EN 10204 3.1/3.2, including chemical analysis, mechanical properties, zinc coating weight verification per ASTM A90 / EN ISO 1460, salt spray test results per ASTM B117, surface quality inspection, and complete heat number traceability.
Comprehensive Specification Range
Thickness 0.12-4.0mm, width 600-1500mm, zinc coating Z40-Z600 g/m². Available in coil (3-12 tons) or cut-to-length sheets. Multiple substrate grades from general forming (DX51D+Z) to extra deep drawing (DX54D+Z) and structural high strength (S280GD/S350GD).
Long-term Corrosion Protection
Hot-dip zinc coating provides dual protection (barrier + cathodic) with typical service life 20-50 years. Z275 coating offers 50+ years protection in normal urban environments. Salt spray test ≥240 hours to 5% red rust for Z275 coating per ASTM B117.
Multiple Surface Options
Three spangle options (regular, minimum, zero spangle), surface treatments (chromated Cr3+/Cr6+, oiled with anti-finger print, unoiled, skin-passed), and edge options (mill edge, slit edge). Custom anti-finger print coating available for visible architectural applications.
Fast Container Loading Worldwide
Common specifications maintained in large stock for 7-15 days dispatch. Container loading optimized for 24-26 tons per 20FT FCL or 25-27 tons per 40FT FCL. Established export logistics to construction contractors, PPGI processors, and OEM manufacturers in over 80 countries.
🏭 Applications of Galvanized Steel Sheet (GI Sheet)
Galvanized steel sheet (GI sheet) is the primary material for construction roofing and wall cladding applications worldwide, including corrugated metal roofing for residential, agricultural, and industrial buildings, IBR (Inverted Box Rib) roofing profiles, standing seam metal roofs, trapezoidal sheets, and architectural wall panels for commercial structures, warehouses, factories, and shopping centers. The construction industry also uses GI sheet for steel framing, light gauge structural members, drywall studs, ceiling tiles, metal door frames, window frames, gutters, downspouts, and rainwater collection systems where long-term corrosion protection is essential. The HVAC and ductwork industry employs GI sheet for air conditioning ducts, ventilation systems, exhaust hoods, smoke vents, kitchen exhaust ductwork, and industrial ventilation equipment requiring excellent corrosion resistance and easy fabrication characteristics. Household appliance manufacturers use GI sheet for refrigerator outer panels, washing machine cabinets, water heater tanks (electric and gas), dishwasher panels, microwave oven exteriors, and small appliance housings, often as raw material for downstream painting or color coating processes. The automotive industry uses GI sheet for body panels (especially for galvanized car bodies), chassis components, fuel tank manufacturing, exhaust system heat shields, and underbody parts requiring corrosion protection. Other major applications include grain storage silos, livestock farming equipment (chicken cages, pig pens), garage doors and shutters, fence panels and posts, highway guardrails and crash barriers, electrical enclosures and switchboards, transformer housings, traffic sign substrates and posts, road sign manufacturing, container and trailer manufacturing, prefabricated steel buildings, and as the primary substrate for prepainted galvanized (PPGI) sheet production used in colored roofing and architectural cladding worldwide.
📋 Quality & Certification
Our Certifications
- ✅ ISO 9001:2015
- ✅ CE Marking
- ✅ ABS
- ✅ DNV GL
- ✅ Lloyd's Register (LR)
- ✅ Bureau Veritas (BV)
- ✅ SGS Certified
- ✅ NK
- ✅ RINA
Mill Certificate Type
- 📋 EN 10204 3.1
- 📋 EN 10204 3.2
- 📋 Original Mill Certificate
- 📋 Third Party Inspection Available
- 📋 Certificate of Origin
❓ Frequently Asked Questions
What is galvanized steel sheet (GI sheet)?
Galvanized steel sheet, commonly called GI sheet, is a carbon steel sheet coated with a layer of zinc through the hot-dip galvanizing process to provide excellent corrosion protection. The zinc coating provides dual protection mechanisms: barrier protection where the zinc layer physically separates steel from corrosive environments, and sacrificial cathodic protection where zinc preferentially corrodes to protect exposed steel at cuts and scratches. GI sheet is specified under JIS G3302 / ASTM A653 / EN 10346 standards, with zinc coating weight from Z40 (40 g/m²) to Z600 (600 g/m²) per side. It is one of the most widely used coated steel products globally for roofing, construction, HVAC, automotive, and appliance manufacturing applications with typical service life of 20-50 years.
What is the difference between Z80, Z180, and Z275 zinc coating?
Zinc coating weight is specified in g/m² total (both sides combined per EN standard) or per side (per JIS standard). Z80 means 80 g/m² total zinc weight (40 g/m² per side, equivalent to ~6 microns thickness per side), suitable for indoor applications and short-term outdoor use with 5-15 years typical service life. Z180 means 180 g/m² total (90 g/m² per side, ~13 microns per side), suitable for general construction roofing and most HVAC applications with 20-30 years service life. Z275 means 275 g/m² total (137.5 g/m² per side, ~20 microns per side), the most common heavy-duty coating for construction roofing, agricultural buildings, and outdoor structures with 30-50+ years service life. Higher coatings Z350-Z600 are used for severe industrial environments and coastal applications. Zinc coating weight directly correlates with corrosion resistance and service life.
What is the difference between DX51D+Z, DX52D+Z, DX53D+Z, and DX54D+Z grades?
These EN 10346 substrate grades indicate increasing formability for deep drawing applications. DX51D+Z is the standard general-purpose grade for forming, bending, and roll forming with elongation ≥22%, suitable for roofing sheets, simple panels, and most HVAC ductwork. DX52D+Z is for deep drawing applications with improved formability (elongation ≥26%), used for moderately complex stamped parts. DX53D+Z is for deep drawing with elongation ≥30%, suitable for complex stamped automotive and appliance parts. DX54D+Z is the extra deep drawing grade with elongation ≥36% and tighter chemistry control (low carbon, often Ti-stabilized), used for very deep drawn parts like washing machine drums, refrigerator inner liners, and complex automotive panels. The 'D' designation indicates 'Drawing' grade. For structural applications, S280GD+Z (yield ≥280 MPa) and S350GD+Z (yield ≥350 MPa) provide higher strength.
What is the difference between regular spangle, minimum spangle, and zero spangle?
Spangle refers to the visible crystalline pattern formed by zinc crystallization during cooling after hot-dip galvanizing. Regular spangle (RS) shows large, visible six-pointed star-shaped crystals 5-50mm in size, the natural result of standard galvanizing process. It provides the most economical option but the visible spangle pattern may show through paint applied later. Minimum spangle (MS) has fine spangle pattern less than 5mm, achieved by adding small amounts of antimony or lead to the zinc bath, providing smoother appearance for visible architectural applications. Zero spangle (ZS), also called regular zero or smooth surface, is achieved through controlled cooling, special bath chemistry, or skin pass rolling, providing virtually invisible spangle pattern with smooth uniform appearance. Zero spangle is essential for prepainted (PPGI) production, architectural visible applications, and appliance manufacturing where surface aesthetics are critical.
What is the typical container loading for galvanized steel sheet?
Standard container loading for galvanized steel sheet: 20FT FCL container typically loads 24-26 tons of GI coils with proper bracing using wooden cradles, steel chocks, and securing straps. Loading capacity varies based on coil weight - larger coils (8-12 tons each) load 3-4 coils per 20FT FCL, while smaller coils (3-5 tons each) load 5-6 coils. 40FT FCL container typically loads 25-27 tons (limited by container weight capacity, not volume). For cut-to-length sheets in pallets, 20FT FCL loads 22-25 tons depending on pallet dimensions and stack heights. All shipments include moisture-proof PE film wrapping, eye protection rings on coils, and weather-resistant tagging. For premium architectural applications requiring zero damage tolerance, additional wooden cradles and individual sheet protection films are applied to prevent surface scratching during ocean transit.
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