S355NL vs S355NLO material Different

S355NL vs S355NLO Material Differences

At Gangsteel, we’re committed to helping engineers understand the key differences between S355NL vs S355NLO, two high-strength, low-alloy structural steels designed for demanding applications, particularly in offshore and cold-climate environments. S355NL, under EN 10025-3, is a normalized fine-grain steel with 355 MPa yield strength and -50°C toughness, ideal for general structural use in cold climates. S355NLO, under EN 10225-3, is a specialized offshore grade based on S355NL, with stricter controls for weldability, low-temperature performance, and resistance to lamellar tearing.

As part of the en 10025 3 normalized steel plate family, both grades offer reliable strength, but S355NLO is optimized for harsh marine conditions. Gangsteel compares their chemical composition, mechanical properties, and applications, with ties to grades like en 10025 3 s355n normalized structural steel plate and en 10025 3 s420n normalized structural steel plate. For stock, quotes, or further details, contact us or visit our en 10025 3 s355nl normalized structural steel plate page.

Overview of S355NL and S355NLO

• S355NL (EN 10025-3, 1.0546): A normalized or normalized rolled fine-grain structural steel with 355 MPa yield strength and -50°C toughness, designed for general high-strength applications in cold climates, such as wind towers and bridges.
• S355NLO (EN 10225-3): An offshore-specific grade (also known as S355G10+N in older standards), based on S355NL but with enhanced weldability, lower phosphorus/sulfur, and stricter through-thickness ductility requirements to prevent hydrogen-induced cracking and lamellar tearing in marine environments.

S355NL is versatile for standard structural use, while S355NLO is tailored for fixed offshore structures, offering superior performance in corrosive, low-temperature conditions.

Chemical Composition Comparison

The chemical composition of S355NL vs S355NLO reflects S355NLO’s stricter offshore requirements:

Carbon Equivalent (CEV):

• S355NL: ≤0.43% (≤63 mm).
• S355NLO: ≤0.41% (≤63 mm).

S355NLO’s lower sulfur (0.010% vs 0.020%), phosphorus (0.020% vs 0.025%), and nitrogen (0.015% vs 0.025%) reduce risks of cracking and tearing in offshore welding, while maintaining similar strength.

Mechanical Properties Comparison

S355NL and S355NLO mechanical properties are nearly identical, with S355NLO having stricter testing:

• Yield Strength: Both offer 355 MPa, suitable for moderate-load structures.
• Tensile Strength: Identical (470-630 MPa), ensuring comparable durability.
• Elongation: Both ≥22%, supporting complex designs.
• Impact Toughness: Both ≥27 J at -50°C, ideal for cold climates.
• Through-Thickness: S355NLO mandates Z25/Z35 for lamellar tearing resistance, while S355NL offers optional Z-quality.
• Thickness: Both up to 200 mm, but S355NLO extends to 255 mm for offshore use.

S355NLO’s mandatory Z-quality ensures better weld integrity in thick plates.

Processing and Fabrication

• S355NL: Normalized for fine-grain microstructure, suited for standard welding. Preheating not typically required for <20 mm; optional for thicker plates. CEV ≤0.43%.
• S355NLO: Normalized with stricter impurity controls for offshore welding; lower CEV (≤0.41%) and mandatory PWHT for thick sections (>100 mm).

Consumables: Both use ER70S-6 (GMAW) and EM12K flux with EH14 wire (SAW). S355NLO’s lower impurities reduce hydrogen cracking risks.

Applications

• S355NL: General high-strength structures in cold climates, like wind towers and bridges, leveraging -50°C toughness.
• S355NLO: Offshore platforms, subsea installations, and marine structures, where mandatory Z-quality and low impurities prevent failure in corrosive, low-temperature conditions.

S355NLO is the premium choice for offshore, while S355NL suits cost-effective cold-climate projects.

Key Differences Summarized

Why Choose Gangsteel?

Gangsteel supplies S355NL and S355NLO:

• Inventory: Extensive stock in China.
• Sizes: Thicknesses 6–200 mm (S355NL), up to 255 mm (S355NLO).
• Delivery: 7-30 days globally.
• Certifications: EN 10204 3.1/3.2, UT testing (EN 10160), DNV/GL approvals for offshore.
• Processing: Cutting, welding, bending.

Contact us for en 10025 3 s355nl normalized structural steel plate.

FAQ

What is the main difference between S355NL and S355NLO?S355NL is a general structural steel under EN 10025-3, while S355NLO is an offshore-specific grade under EN 10225-3 with stricter impurity limits and mandatory Z-quality.

How do S355NL and S355NLO toughness compare?Both offer ≥27 J at -50°C, but S355NLO’s lower N (0.015% vs 0.025%) and S (0.010% vs 0.020%) minimize cracking risks.

Which is better for offshore welding, S355NL or S355NLO?S355NLO’s mandatory Z25/Z35 and lower impurities make it superior for offshore welds, reducing lamellar tearing.

What applications suit S355NL vs S355NLO?S355NL is for cold-climate bridges and wind towers; S355NLO is for offshore platforms and subsea structures.

How do S355NL and S355NLO costs compare?S355NLO is 10-15% more expensive due to stricter offshore specifications.

What certifications support S355NL and S355NLO?Gangsteel provides both with EN 10204 3.1/3.2, UT testing, and DNV/GL approvals for offshore compliance.

Summary

S355NL and S355NLO are high-strength structural steels with 355 MPa yield strength and -50°C toughness, but S355NLO is optimized for offshore use with stricter impurity controls.

S355NL (EN 10025-3) suits general cold-climate applications like wind towers, while S355NLO (EN 10225-3) excels in marine structures with mandatory Z-quality to prevent tearing.

Gangsteel’s inventory supports thicknesses up to 200 mm (S355NL) and 255 mm (S355NLO), with global delivery in 7-30 days and certifications like EN 10204 3.1/3.2.

S355NLO’s enhanced weldability and toughness make it the premium choice for harsh environments, while S355NL offers cost-effective performance for standard cold-climate projects.