GB/T700 & GB/T1591 Carbon Steel Coils: Versatile Structural Steel for Infrastructure Projects
Product Overview
GB/T700 (Q235-Q275) and GB/T1591 (Q345-Q690) carbon steel coils are general-purpose structural steels compliant with China GB/T700, GB/T1591, and EN 10025-2 S275JR/S355JR. Designed for bridges, highways, and industrial frameworks, these coils deliver 235–690 MPa yield strength and 15–26% elongation while balancing cost-effectiveness with weldability. Available in grades Q235 (mild steel) to Q690 (high-strength), they meet diverse load-bearing needs without heat treatment.
Key Technical Specifications
1. Production & Dimensions
- Process:
- Hot-rolled: 2.75–100mm (±1.2% thickness tolerance)
- Cold-rolled: 0.2–3mm (±0.5% tolerance)
- Width: 45–2,200mm (suitable for automated beam cutting)
- Surface: Mill scale (Ra 12.5µm), wire-drawn (Ra 3.2µm), or laminated film (anti-corrosion)
2. Chemical Composition
| Grade | C (≤) | Mn (≤) | Si (≤) | P (≤) | S (≤) | CEV (IIW) |
|---|---|---|---|---|---|---|
| Q235B | 0.20% | 0.70% | 0.30% | 0.045% | 0.045% | 0.29 |
| Q345D | 0.18% | 1.70% | 0.50% | 0.030% | 0.025% | 0.42 |
| Q460E | 0.20% | 1.70% | 0.80% | 0.020% | 0.010% | 0.55 |
Trace elements: Cu ≤0.30%, Cr ≤0.30%, Ni ≤0.30%
Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Impact (-20°C) |
|---|---|---|---|---|
| Q235B | 235 | 370–500 | 24 | 27J |
| Q345D | 345 | 470–630 | 22 | 34J |
| Q460E | 460 | 550–720 | 17 | 40J |
Tested per GB/T 228.1 (metallic materials) & GB/T 229 (Charpy impact)
Performance Advantages
- Cost-Effective Fabrication:
- Bend radius: 2.5× thickness (Q235B, cold-formed per GB/T 232).
- Welding speed: 1.2 m/min with E7018 electrodes (Q345D, 10mm plate).
- Low-Temperature Toughness:
- Charpy V-notch: 40J at -20°C (Q460E, 25mm thickness).
- Ideal for Siberian pipeline supports and Arctic warehouses.
- Corrosion Resistance:
- Atmospheric corrosion rate: 0.075 mm/year (ISO 9223 C2 environments).
- Compatible with galvanizing (610 g/m² zinc coating).
- Thermal Properties:
- Thermal conductivity: 51 W/m·K (Q235B at 20°C)
- Expansion coefficient: 11.7 µm/m°C (20–100°C)
Applications by Grade
| Grade | Industry | Use Case |
|---|---|---|
| Q235B | Construction | Steel framing, guardrails |
| Q345D | Energy | Wind turbine towers |
| Q460E | Heavy Machinery | Mining truck chassis |
Global Equivalents
| GB/T Standard | EN 10025 | ASTM | JIS G3101 |
|---|---|---|---|
| Q235B | S275JR | A36 | SS400 |
| Q345D | S355J2 | A572 Gr.50 | SM490YB |
| Q460E | S460ML | A633 Gr.E | SHN690 |
Sustainability & Compliance
- Recycled Content: 85% (mill-certified)
- RoHS Compliance: Lead <0.01%, Mercury-free
- Certifications: CE Mark EN 1090-1, ISO 1461 (galvanized)
Packing And Delivery
