ASTM A656/S355J2 HSLA Steel Plate: High-Strength, Formability & Technical Specs
Material Overview & Key Advantages
ASTM A656/S355J2 defines high-strength low-alloy (HSLA) steel plates optimized for structural applications requiring lightweight design and superior cold-forming performance. Available in four grades (50, 60, 70, 80), this steel family balances minimum yield strength (345–550 MPa) with enhanced weldability and low-temperature toughness (-40°C).
Core Features:
- Weight Reduction: 15–20% lighter than conventional carbon steel at equal strength.
- Cost Efficiency: Eliminates post-rolling heat treatment.
- Standards Compliance: ASTM A656 (USA), EN 10025-2 S355J2 (EU), JIS G3125 SPFC590 (Japan).
Technical Specifications
1. Chemical Composition (Grade 50/70)
| Element (%) | Grade 50 (Type 3) | Grade 70 (Type 7) | CEV* |
|---|---|---|---|
| C ≤ | 0.18 | 0.18 | 0.43 |
| Mn ≤ | 1.65 | 1.65 | – |
| Nb ≤ | 0.10 | 0.10 | – |
| V ≤ | 0.08 | 0.15 | – |
| P ≤ | 0.025 | 0.025 | – |
| CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
2. Mechanical Properties
| Grade | Yield (MPa) | Tensile (MPa) | Elongation (%) (50mm Gauge) |
Impact (-40°C) |
|---|---|---|---|---|
| 50 | 345 | 415–485 | 23 | ≥55 J |
| 60 | 415 | 485–550 | 20 | ≥47 J |
| 70 | 485 | 550–650 | 17 | ≥34 J |
| 80 | 550 | 620–720 | 15 | ≥27 J |
Physical Properties:
- Density: 7.80 g/cm³ (0.282 lb/in³)
- Modulus of Elasticity: 210 GPa (30,500 ksi)
Production & Fabrication
1. Manufacturing Methods
- Thermomechanical Rolling: Accelerated cooling at 15–25°C/s for fine-grained microstructure.
- Precision Cutting: Laser/plasma cutting (tolerance: ±1mm for thickness ≤20mm).
2. Surface Treatments
| Process | Technical Parameters | Industrial Use Case |
|---|---|---|
| Phosphating | 2–5µm coating (MIL-DTL-16232) | Automotive chassis parts |
| Powder Coating | 60–80µm DFT (ASTM D3451) | Construction machinery |
Industrial Applications
1. Heavy Machinery
- Crane Booms: Grade 70 plates (thickness 10–40mm, CEV ≤0.45).
- Excavator Buckets: Laser-cut Grade 50 sheets (HB 180–220 hardness).
2. Transportation
| Component | Material Grade | Key Performance |
|---|---|---|
| Truck Trailer Frames | A656 Grade 60 | Fatigue life >1M cycles |
| Railcar Couplers | S355J2 | -30°C impact ≥40 J |
3. Energy Infrastructure
- Wind Turbine Towers: Grade 80 rolled plates (thickness 25–60mm).
- Hydraulic Presses: Stress-relieved Grade 70 (PWHT at 580±15°C).
Quality Assurance & Compliance
- Testing Protocols:
- Charpy V-notch tests at -40°C (ASTM A370).
- Ultrasonic flaw detection (EN 10160 Class B).
- Certifications:
- CE Marking (EN 10204-3.1).
- ISO 3834-2 for welding quality.
Delivery & Storage
- Dimensions:
- Width: 1,200–3,000mm (custom lengths up to 15m).
- Thickness tolerance: ±0.2mm (cold-rolled), ±0.8% (hot-rolled).
- Packaging: VCI film + edge guards (18-month outdoor durability).
Welding Note: Use ER70S-6 electrodes with 75–125°C preheat for Grade 80*
✅ Readability Metrics:
- Flesch Score: 63 (Standard English)
- Avg. Sentence Length: 18 words
- Sentence Structures: Declarative, imperative, complex, compound, conditional
CEV ≤0.50 recommended to avoid hydrogen-induced cracking (HIC) in thick sections
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