What is s355nlo material?

What is S355NLO Material?

S355NLO is a high-strength, low-alloy structural steel grade specifically designed for offshore and marine applications, as defined under the European standard EN 10225-3:2019 (Steel for the fabrication of offshore structures – Weldable structural steels for fixed offshore structures). It is a variant of the S355NL grade, optimized for enhanced weldability, low-temperature toughness, and resistance to lamellar tearing in harsh environments. The "NLO" suffix stands for:

• N: Normalized or normalized rolled (fine-grain structure).
• L: Low temperature toughness (tested at -50°C).
• O: Offshore grade (with stricter requirements for corrosion resistance, weldability, and through-thickness ductility).

S355NLO is also known as S355G10+N in older standards and is commonly used in the fabrication of fixed offshore platforms, subsea structures, and other marine installations where reliability under cyclic loading and corrosive conditions is critical. It belongs to Group 2 steels in EN 10225, offering good tensile and yield strength while minimizing risks like hydrogen-induced cracking.

Key Characteristics

• Yield Strength: Minimum 355 MPa (for thicknesses ≤16 mm), decreasing with thickness.
• Tensile Strength: 470-630 MPa.
• Toughness: ≥27 J at -50°C (Charpy V-notch impact test).
• Material Number: 1.8808 (or similar under EN 10225).
• Processing: Normalized or normalized rolled to achieve a fine-grain microstructure.

S355NLO is produced with low phosphorus and sulfur contents to improve weldability and resistance to lamellar tearing, making it suitable for thick plates (up to 255 mm) in offshore welding.

Chemical Composition

The chemical composition of S355NLO is tightly controlled to ensure offshore suitability:

Carbon Equivalent (CEV): ≤0.43% for thicknesses up to 63 mm, ensuring excellent weldability in offshore fabrication.

Mechanical Properties

S355NLO's properties are optimized for offshore demands:

• Hardness: Typically 150-190 HB (Brinell).
• Density: 7.85 g/cm³ (7850 kg/m³).

These properties ensure S355NLO's suitability for fixed offshore structures, with good resistance to low temperatures and cyclic loading.

Applications of S355NLO Material

S355NLO is primarily used in:

• Offshore Platforms: Weldable plates for fixed structures, subsea installations, and risers, leveraging its low lamellar tearing risk.
• Marine Engineering: Components in ships, rigs, and harbors, benefiting from corrosion resistance and toughness.
• Cold-Environment Infrastructure: Bridges and towers in northern regions, where -50°C performance is essential.
• Heavy Fabrication: Thick plates for welded assemblies, ensuring structural integrity.

Compared to standard S355NL (EN 10025-3), S355NLO has stricter controls for offshore use, including lower P and S levels.

Welding and Fabrication

• Weldability: Excellent (CEV ≤0.43%), with low preheating requirements (<20 mm thickness).
• Consumables: ER70S-6 for GMAW; EM12K flux with EH14 wire for SAW.
• Heat Treatment: PWHT optional at 550-650°C for thick sections.

Why Choose Gangsteel for S355NLO?

Gangsteel, a leading producer and exporter, supplies S355NLO with:

• Inventory: Extensive stock in China.
• Sizes: Thicknesses 6–255 mm, widths up to 3000 mm, lengths up to 12,000 mm.
• Delivery: 7-30 days globally.
• Certifications: EN 10204 3.1/3.2, UT testing (EN 10160), and DNV/GL approvals for offshore compliance.
• Processing: Cutting, welding, bending.

Contact us for quotes or stock at our offshore steel plates page.

FAQ

What is S355NLO material?S355NLO is a high-strength structural steel for offshore structures under EN 10225-3, with 355 MPa yield strength and -50°C toughness, optimized for weldability.

How does S355NLO differ from S355NL?S355NLO has stricter controls (lower P/S) for offshore use, while S355NL is general-purpose with similar properties.

What are S355NLO's key properties?S355NLO offers 355 MPa yield strength, 470-630 MPa tensile strength, ≥22% elongation, and ≥27 J at -50°C.

Is S355NLO suitable for offshore welding?Yes, its low CEV (≤0.43%) and reduced impurities ensure excellent weldability with minimal preheating.

What applications use S355NLO?S355NLO is used in offshore platforms, subsea structures, and marine engineering for its toughness and corrosion resistance.

What certifications support S355NLO?Gangsteel provides S355NLO with EN 10204 3.1/3.2, UT testing, and DNV/GL approvals for offshore compliance.

Summary

S355NLO is a specialized high-strength steel for offshore structures under EN 10225-3, offering 355 MPa yield strength and -50°C toughness.

Its low-alloy composition with minimized P/S ensures weldability and resistance to lamellar tearing, ideal for fixed platforms and subsea installations.

Gangsteel’s stock ranges from 6–255 mm thickness, with global delivery in 7-30 days and offshore certifications.

Compared to S355NL, S355NLO’s stricter specs make it the go-to for marine environments, providing durability in harsh conditions.