What is S355NL steel grade?

S355NL Steel Grade

What is S355NL Steel Grade?

S355NL is a high-strength, low-alloy structural steel grade specified under the European standard EN 10025-3, which covers normalized or normalized rolled weldable fine grain structural steels. The designation "S355NL" breaks down as follows:

• S: Structural steel.
• 355: Minimum yield strength of 355 MPa for thicknesses up to 16 mm.
• NL: Normalized or normalized rolled, with impact toughness tested at -50°C for enhanced low-temperature performance.

As a fine grain structural steel, S355NL is engineered with a refined microstructure to provide excellent toughness, weldability, and resistance to brittle fracture, making it ideal for demanding applications in cold environments such as bridges, offshore platforms, and wind turbine towers. For more details, explore our EN 10025-3 S355NL normalized structural steel plate.

Chemical Composition of S355NL

The chemical composition of S355NL is tightly controlled to ensure a balance of strength, toughness, and weldability. Below is the ladle analysis (melt stage) and product analysis (finished plate) as per EN 10025-3:

The Carbon Equivalent (CEV), calculated as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, is ≤0.43% for thicknesses ≤63 mm, ensuring excellent weldability with minimal risk of cold cracking.

Mechanical Properties of S355NL

S355NL offers a robust combination of strength, ductility, and low-temperature toughness. Its key mechanical properties include:

• Yield Strength: ≥355 MPa (≤16 mm).
• Tensile Strength: 470-630 MPa.
• Elongation: ≥22% (≤63 mm).
• Impact Toughness: ≥27 J at -50°C (Charpy V-notch, longitudinal).

Properties vary with thickness, as shown below:

These properties make S355NL suitable for high-stress, cold-environment applications.

Equivalent Grades of S355NL

S355NL has equivalents across international standards, though slight variations exist:

For the -20°C variant, see EN 10025-3 S355N normalized structural steel plate.

Welding and Heat Treatment

S355NL’s low CEV (≤0.43%) ensures excellent weldability using GMAW or SAW, per EN 1011-2 guidelines.

• Preheating: Not required for ≤20 mm; 100-150°C advised for thicker plates to prevent hydrogen cracking.
• Post-Weld Heat Treatment (PWHT): Typically unnecessary; stress relief at 550-650°C optional for critical welds.
• Recommended Consumables: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).

Applications of S355NL Steel Grade

S355NL is widely used in industries requiring strength and low-temperature performance:

• Offshore Platforms: Fatigue-resistant in cold marine environments.
• Wind Turbine Towers: Supports heavy loads in sub-zero climates.
• Bridges and Cranes: Load-bearing components in northern regions.
• Pressure Vessels: For low-temperature storage or processing.

Its high strength-to-weight ratio, -50°C toughness, and weldability align with Eurocode 3 for safe, efficient designs. Explore related grades like EN 10025-3 S420NL normalized structural steel plate.

Why Choose Gangsteel for S355NL?

Gangsteel is a trusted supplier of S355NL:

• Inventory: Extensive stock in China for rapid delivery.
• Sizes: Thickness 6–250 mm, widths 2000/2500/3000 mm, lengths up to 12,000 mm.
• Delivery: 7-30 days globally to Europe, Asia, Middle East, Americas.
• Certifications: EN 10204 3.1/3.2, UT testing (EN 10160), ABS/LR/BV/DNV approvals.
• Processing: Cutting, welding, bending to specifications.

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

FAQ

What is S355NL steel grade used for?It’s used in offshore platforms, wind towers, bridges, and pressure vessels in cold climates due to its -50°C toughness.

How does S355NL differ from S355N?S355NL is tested at -50°C, S355N at -20°C, making S355NL better for colder environments. See EN 10025-3 S355N normalized structural steel plate.

Is S355NL weldable?Yes; its CEV ≤0.43% supports GMAW/SAW with minimal preheating (100-150°C for >20 mm).

What is the ASTM equivalent of S355NL?ASTM A572 Grade 65 (yield ~450 MPa) is closest in strength, but A633 Grade E better matches -50°C toughness.

What is the maximum thickness of S355NL?Up to 250 mm, with adjusted mechanical properties.

Can S355NL be used in arctic conditions?Yes; its -50°C impact resistance suits arctic offshore and wind structures with proper coatings.

How does S355NL compare to S420NL?S420NL has higher yield (420 MPa vs 355 MPa), both tested at -50°C. Check EN 10025-3 S420NL normalized structural steel plate.

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