ASTM A656/S355J2 Carbon Steel Coil: High-Strength Structural Steel for Lightweight Applications
Product Overview
ASTM A656/S355J2 carbon steel coil is a high-strength low-alloy (HSLA) steel compliant with ASTM A656, EN 10025-2 S355J2, and JIS G3135 SPFH590. Designed for crane booms, truck frames, and construction machinery, this steel delivers 345–690 MPa yield strength and 12–23% elongation while reducing structural weight by 15–25% compared to traditional steels like A36. Available in Grades 50, 60, 70, and 80, it combines hot/cold rolling precision with excellent low-temperature toughness (-50°C).
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 robotic welding systems)
- Surface: Mill scale (Ra 8.3µm), wire-drawn (Ra 2.5µm), or laminated film (anti-scratch)
2. Chemical Composition
| Grade | C (≤) | Mn (≤) | Si (≤) | V | Nb | CEV (IIW) |
|---|---|---|---|---|---|---|
| 50 | 0.18% | 1.65% | 0.60% | 0.08% | 0.008–0.10% | 0.37 |
| 70 | 0.18% | 1.65% | 0.60% | 0.15% | 0.10% | 0.45 |
Trace elements: P ≤0.025%, S ≤0.035%, N ≤0.020%
Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Impact Toughness (-50°C) |
|---|---|---|---|---|
| 50 | 345 | 415–550 | 18 (200mm) | 34J |
| 60 | 415 | 485–650 | 17 (200mm) | 28J |
| 70 | 485 | 550–700 | 14 (200mm) | 22J |
| 80 | 550 | 620–750 | 12 (200mm) | 18J |
Tested per ASTM A370 (transverse specimens)
Performance Advantages
- Strength-to-Weight Optimization:
- 25% weight reduction vs. A572 steel in crane boom designs (Grade 70, 10mm thickness).
- Bend radius: 2.5× thickness (ASTM A6/A6M compliant).
- Weldability & Fabrication:
- Carbon Equivalent (CEV): 0.37–0.45 (IIW formula) minimizes preheating below 25mm.
- Recommended welding: GMAW (ER70S-3 wire) or laser welding for thin sheets.
- Low-Temperature Performance:
- Charpy V-notch impact: 22J at -50°C (Grade 70, 20mm thickness).
- Ideal for Arctic mining equipment and cold-storage facilities.
- Corrosion Resistance:
- Atmospheric corrosion rate: 0.055 mm/year (ISO 9223 C3 environments).
- Compatible with epoxy coatings (DFT 120µm).
Applications by Grade
| Grade | Industry | Use Case |
|---|---|---|
| 50 | Automotive | Truck chassis, trailer frames |
| 60 | Logistics | Container handling cranes |
| 70 | Energy | Hydraulic turbine components |
| 80 | Defense | Military vehicle armor plates |
Global Equivalents
| ASTM A656 | EN 10025 | JIS G3135 | GB/T 1591 |
|---|---|---|---|
| Grade 50 | S355J2 | SPFH590 | Q345D |
| Grade 70 | S460ML | SPFH690 | Q460E |
Sustainability & Compliance
- Recycled Content: 82% (mill-certified)
- RoHS Compliance: Lead <0.01%, Cadmium-free
- CE Marking: EN 1090-1 (Execution Class 2)
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