As a professional steel manufacturer with over 18 years of experience, GNEE specializes in supplying high-performance structural steel plates to global industries including construction, offshore engineering, energy, and heavy equipment.
When selecting the right material, understanding the S355J2 vs S355NL difference is essential. S355J2 vs S355NL difference directly affects low-temperature performance, structural safety, and long-term reliability, especially in demanding environments such as cold regions or offshore projects.
S355J2 vs S355NL Difference – Basic Definition and Standards
What is S355NL?
S355NL is a high-strength, fine-grained structural steel under EN 10025-3, delivered in a normalized or normalized rolled condition. The designation breaks down as:
- S: Structural steel.
- 355: Minimum yield strength of 355 MPa for thicknesses up to 16 mm.
- NL: Normalized with impact toughness tested at -50°C.
It's designed for low-temperature applications, offering excellent toughness and weldability due to its fine grain structure.
What is S355J2?
S355J2 is a non-alloy structural steel under EN 10025-2, typically supplied in a hot-rolled condition. Its designation means:
- S: Structural steel.
- 355: Minimum yield strength of 355 MPa for thicknesses up to 16 mm.
- J2: Impact toughness tested at -20°C.
S355J2 is a general-purpose steel for structural applications in moderate environments, valued for its cost-effectiveness and ease of fabrication.
Chemical Composition Comparison
The chemical compositions of S355NL and S355J2 differ due to their standards' focus on fine grain (S355NL) versus non-alloy (S355J2) properties.
|
Element |
S355NL (EN 10025-3, Ladle Analysis, max %) |
S355J2 (EN 10025-2, max %) |
|---|---|---|
|
Carbon (C) |
0.18 |
0.20 |
|
Silicon (Si) |
0.50 |
0.55 |
|
Manganese (Mn) |
0.90-1.65 |
1.60 |
|
Phosphorus (P) |
0.025 |
0.025 |
|
Sulfur (S) |
0.015 |
0.025 |
|
Nitrogen (N) |
0.015 |
Not specified |
|
Aluminum (Al) |
0.02 (min, total) |
Not specified |
|
Niobium (Nb) |
0.05 |
Not specified |
|
Vanadium (V) |
0.12 |
Not specified |
|
Titanium (Ti) |
0.05 |
Not specified |
|
Chromium (Cr) |
0.30 |
0.30 |
|
Nickel (Ni) |
0.30 |
0.30 |
|
Molybdenum (Mo) |
0.10 |
Not specified |
|
Copper (Cu) |
0.55 |
0.55 |
Carbon Equivalent (CEV):
- S355NL: ≤0.43% (≤63 mm), ensuring excellent weldability due to fine grain control and low impurities.
- S355J2: ≤0.45% (≤40 mm), slightly higher due to less stringent alloy control, but still weldable.
S355NL's tighter limits on sulfur, phosphorus, and nitrogen, plus mandatory aluminum for grain refinement, enhance its toughness and weldability compared to S355J2.
Mechanical Properties Comparison
Both grades share similar yield and tensile strengths, but their toughness and temperature performance differ significantly.
|
Property |
S355NL (EN 10025-3) |
S355J2 (EN 10025-2) |
|---|---|---|
|
Yield Strength (min, MPa) |
||
|
≤16 mm |
355 |
355 |
|
16 |
345 |
345 |
|
40 |
335 |
335 |
|
Tensile Strength (MPa) |
||
|
≤16 mm |
470-630 |
470-630 |
|
16 |
470-630 |
470-630 |
|
Elongation (min, %) |
22 (≤63 mm) |
22 (≤40 mm) |
|
Impact Energy (min, J) |
27 @ -50°C (longitudinal) |
27 @ -20°C (longitudinal) |
Key Differences:
- Impact Toughness: S355NL is tested at -50°C, making it suitable for colder climates (e.g., arctic or offshore structures), while S355J2's -20°C testing limits it to milder conditions.
- Thickness Range: S355NL maintains properties up to 250 mm, while S355J2 is typically specified up to 250 mm but with less stringent low-temperature guarantees.
S355J2 vs S355NL Difference – Manufacturing Process
S355J2 Production
- Hot rolled
- Optional normalization (+N)
- Standard grain structure
S355NL Production
- Mandatory normalization rolling
- Fine grain structure control
- Strict process control
Process Impact
S355NL's controlled rolling and normalizing process ensures:
- Uniform mechanical properties
- Fine grain structure
- Superior resistance to brittle fracture
Welding and Heat Treatment
S355NL: Its low CEV (≤0.43%) and fine grain structure make it highly weldable using GMAW or SAW. Preheating (100-150°C) is recommended for thicknesses >20 mm; post-weld heat treatment (PWHT) at 550-650°C is optional for critical welds. Recommended fillers: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).
S355J2: Slightly higher CEV (≤0.45%) but still weldable with similar methods. Preheating is advised for >25 mm; PWHT is rarely needed. Same fillers apply.
S355NL's finer grain and lower impurities reduce the risk of weld imperfections compared to S355J2.
S355J2 vs S355NL Difference – Application Scenarios
S355J2 Applications
- General construction
- Buildings and bridges
- Machinery components
- Moderate climate environments
S355NL Applications
- Offshore platforms
- Pressure vessels
- Cryogenic and low-temperature structures
- Oil & gas pipelines
- Wind towers in cold regions
S355J2 vs S355NL Difference – Advantages Comparison
Advantages of S355J2
- Cost-effective
- Widely available
- Suitable for general structural use
Advantages of S355NL
- Excellent low-temperature performance (-50°C)
- Higher safety margin
- Better weldability and toughness
- Ideal for critical engineering projects
Equivalent Grades
S355NL: Equivalents include Q345E (China), A572 Grade 65 (ASTM, approximate), and StE 355/TStE 355 (DIN). See EN 10025-3 S355N normalized structural steel plate for the -20°C variant.
S355J2: Equivalents include Q345B (China), A572 Grade 50 (ASTM, approximate), and SM490B (JIS).
S355NL's fine-grain normalization gives it an edge in toughness over S355J2's non-alloy structure.
S355J2 vs S355NL Difference – Selection Guide
When to Choose S355J2
- Budget-sensitive projects
- Standard structural applications
- No extreme temperature requirements
When to Choose S355NL
- Low-temperature environments (< -20°C)
- Safety-critical structures
- Offshore or energy projects
- Thick plate applications
👉 Choosing the wrong grade may lead to performance failure in cold conditions, so proper selection is crucial.
S355J2 vs S355NL Difference – Parameter Table
| Parameter | S355J2 | S355NL |
|---|---|---|
| Standard | EN 10025-2 | EN 10025-3 |
| Steel Type | Non-alloy structural | Fine grain structural |
| Heat Treatment | Optional (+N) | Mandatory Normalized |
| Grain Structure | Standard | Fine grain |
| Weldability | Good | Excellent |
| Application Level | General | Critical |
| Cost | Lower | Higher |
S355J2 vs S355NL Difference – Why Choose GNEE?
With extensive experience in global steel supply, GNEE provides:
- Full range of EN standard steel plates
- Advanced testing (impact test, UT, tensile test)
- Strict quality assurance and certifications
- OEM & ODM customization
- Fast delivery and strong logistics network
We have successfully served clients in Europe, Southeast Asia, the Middle East, and South America, ensuring reliable solutions for demanding projects.
FAQ
What is the main difference between S355NL and S355J2?
S355NL (EN 10025-3) is normalized fine-grain steel with -50°C toughness, while S355J2 (EN 10025-2) is hot-rolled non-alloy steel tested at -20°C.
Which is better for cold climates?
S355NL, due to its -50°C impact toughness, is superior for arctic or offshore use.
Are S355NL and S355J2 weldable?
Yes; S355NL's lower CEV (≤0.43%) offers slightly better weldability than S355J2 (≤0.45%).
Which is more cost-effective?
S355J2 is generally cheaper due to simpler hot-rolled processing, ideal for non-critical applications.
Can S355NL replace S355J2?
Yes, in most cases, but S355NL's higher cost and cold toughness may be overkill for temperate environments.
What are typical applications for S355NL vs S355J2?
S355NL: Offshore, wind towers, cold-region bridges. S355J2: General buildings, moderate-climate structures.
How do their equivalents compare?
S355NL aligns with Q345E, S355J2 with Q345B; S355NL's fine-grain structure ensures better low-temp performance.
Explore related grades Comparison： S355NL VS S355J2 N ,S355J2 VS S355J2 N
S355J2 vs S355NL Difference – Conclusion
In conclusion, the S355J2 vs S355NL difference mainly lies in their low-temperature performance and manufacturing process. While S355J2 is suitable for general applications, S355NL provides superior toughness, finer grain structure, and reliable performance in extreme conditions, especially at -50°C.
If your project demands high safety and performance, choosing the right material is critical. Contact GNEE today for expert advice, competitive pricing, and fast quotation on S355J2 vs S355NL steel plates-let us help you secure the best solution for your project!
