s355nl vs s355j2

S355NL vs S355J2: A Detailed Comparison

S355NL and S355J2 are both structural steels under the European standard EN 10025, but they differ significantly in their specifications, properties, and applications. S355NL is specified under EN 10025-3 for normalized fine grain steels, while S355J2 falls under EN 10025-2 for non-alloy structural steels. This article compares their chemical composition, mechanical properties, welding characteristics, and applications to help you choose the right material. For more details, explore our EN 10025-3 S355NL normalized structural steel plate.

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.

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.

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.

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.

Applications

• S355NL: Preferred for low-temperature environments:
  • Offshore platforms and wind towers in cold regions.
  • Bridges and cranes in northern climates.
  • Pressure vessels for low-temperature storage. Its -50°C toughness ensures reliability in harsh conditions. See EN 10025-3 S355NL normalized structural steel plate.
• S355J2: Suited for general structural applications in moderate climates:
  • Building frameworks and commercial structures.
  • Bridges and machinery in temperate regions.
  • General fabrication where cost is a priority.

S355J2 is more economical but less suited for sub-zero conditions compared to S355NL.

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.

Why Choose Gangsteel for S355NL and S355J2?

Gangsteel offers both grades with:

• Inventory: Ample stock in China for S355NL, S355J2, and related grades like EN 10025-3 S420NL normalized structural steel plate.
• Sizes: Thickness 6–250 mm, widths 2000/2500/3000 mm, lengths up to 12,000 mm.
• Delivery: 7-30 days globally.
• Certifications: EN 10204 3.1/3.2, UT testing (EN 10160), ABS/LR/BV/DNV approvals.
• Processing: Cutting, welding, bending.

Contact us for EN 10025-3 S355NL normalized structural steel plate.

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 like EN 10025-3 S275N normalized structural steel plate or EN 10025-3 S460NL normalized structural steel plate.