A572/S355JR High-Strength Low-Alloy (HSLA) Steel Coil: Advanced Structural Steel for Heavy-Duty Applications
A572/S355JR Carbon Steel Coil Product Overview
The A572/S355JR carbon steel coil is a high-strength low-alloy steel offering 345–450 MPa yield strength across Grades 42, 50, 60, and 65, compliant with ASTM A572, EN 10025-2 S355JR, and GB/T 1591 Q345B standards. Designed for bridges, transmission towers, and industrial equipment, this steel combines 18–20% elongation with excellent weldability and weather resistance, outperforming mild steels like A36 in load-bearing efficiency.
Key Technical Specifications
1. Production & Dimensions
- Process:
- Hot-rolled: 2.75–100mm thickness (±1% tolerance)
- Cold-rolled: 0.2–3mm thickness (±0.3% tolerance)
- Width: 45–2,200mm (optimized for CNC cutting/forming)
- 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) |
|---|---|---|---|---|---|---|
| 42 | 0.21% | 1.35% | 0.15–0.40% | 0.03% | 0.03% | 0.38 |
| 50 | 0.23% | 1.35% | 0.15–0.40% | 0.03% | 0.03% | 0.41 |
| 60 | 0.26% | 1.35% | 0.40% | 0.03% | 0.03% | 0.45 |
| 65 | 0.26% | 1.65% | 0.40% | 0.03% | 0.03% | 0.49 |
Trace elements: Cu ≤0.35%, Cr ≤0.20%, Ni ≤0.25%
Mechanical Properties
| Grade | Yield Strength | Tensile Strength | Elongation (200mm) | Charpy Impact (-20°C) |
|---|---|---|---|---|
| 42 | 290 MPa | 415 MPa | 20% | 27J |
| 50 | 345 MPa | 450 MPa | 18% | 27J |
| 60 | 415 MPa | 520 MPa | 16% | 24J |
| 65 | 450 MPa | 550 MPa | 15% | 20J |
Tested per ASTM A370 (longitudinal specimens)
Performance Advantages
- Structural Efficiency:
- 30% weight reduction vs. A36 steel at equivalent load capacity (Grade 50).
- Bend radius: 2× thickness (ASTM A6/A6M for cold-forming).
- Weldability & Fabrication:
- Preheating not required below 25mm thickness (AWS D1.1/D1.8 compliant).
- Carbon equivalent (CEV) ≤0.49 enables MIG/TIG welding without cracking.
- Corrosion Resistance:
- Atmospheric corrosion rate: 0.055 mm/year (ISO 9223 C3 environments).
- Compatible with galvanizing (610g/m²) or epoxy coatings (75µm DFT).
- Thermal Stability:
- Thermal conductivity: 46 W/m·K (20°C)
- Coefficient of expansion: 11.5 µm/m°C (20–100°C)
Applications by Grade
| Grade | Industry | Use Case |
|---|---|---|
| 42 | Civil Eng. | Highway guardrails, signage posts |
| 50 | Energy | Wind turbine bases, transmission poles |
| 60 | Mining | Excavator booms, conveyor frames |
| 65 | Defense | Military vehicle chassis, bridge mats |
Global Equivalents
| ASTM A572 | EN 10025 | JIS G3106 | GB/T 1591 |
|---|---|---|---|
| Grade 42 | S275JR | SM490A | Q295B |
| Grade 50 | S355JR | SM570 | Q345C |
Sustainability & Compliance
- Recycled Content: 89% (mill-certified)
- RoHS Compliance: Lead <0.01%, Mercury-free
- CE Marking: EN 1090-1 (Execution Class 2)
Packing And Delivery
