S355N S355M and S355NL Steel Grades Comparison

S355N, S355M, and S355NL Steel Grades Comparison

At Gangsteel, we’re here to clarify the differences between S355N, S355M, and S355NL, three high-strength, low-alloy structural steels under the EN 10025 standard, each tailored for specific structural applications. S355N and S355NL, under EN 10025-3, are normalized steels with 355 MPa yield strength, differing in toughness (-20°C for S355N, -50°C for S355NL), while S355M, under EN 10025-4, is thermomechanically rolled for enhanced formability.

As part of the en 10025 3 normalized steel plate and EN 10025-4 families, these grades serve distinct purposes in bridges, cranes, and offshore structures. Gangsteel compares their chemical composition, mechanical properties, and applications, with ties to grades like en 10025 3 s420n normalized structural steel plate and en 10025 3 s460n normalized structural steel plate. For more details, contact us or visit our en 10025 3 s355n normalized structural steel plate page.

Overview of S355N, S355M, and S355NL

• S355N (EN 10025-3, 1.0545): A normalized or normalized rolled fine-grain steel with 355 MPa yield strength and -20°C toughness, ideal for moderate climates like temperate Europe.
• S355M (EN 10025-4, 1.8823): A thermomechanically rolled fine-grain steel with 355 MPa yield strength and -20°C toughness, designed for enhanced formability in complex structures.
• S355NL (EN 10025-3, 1.0546): A normalized or normalized rolled fine-grain steel with 355 MPa yield strength and -50°C toughness, suited for cold climates like Arctic regions.

S355N and S355NL are optimized for plates, while S355M is designed for applications requiring improved formability. All three grades are versatile for structural use, with S355NL excelling in low-temperature environments.

Chemical Composition Comparison

The chemical composition of S355N, S355M, and S355NL influences their properties:

Carbon Equivalent (CEV):

• S355N: ≤0.43% (≤63 mm).
• S355M: ≤0.39% (≤63 mm).
• S355NL: ≤0.43% (≤63 mm).

S355M’s lower carbon (0.14%), sulfur (0.020%), phosphorus (0.025%), and nitrogen (0.015%) enhance weldability and formability, while S355NL’s lower carbon (0.18%) and impurities improve toughness compared to S355N, similar to en 10025 3 s420n normalized structural steel plate.

Mechanical Properties Comparison

S355N, S355M, and S355NL mechanical properties highlight their differences:

• Yield Strength: All three grades offer 355 MPa, ideal for moderate-load structures.
• Tensile Strength: S355N and S355NL (470-630 MPa) are slightly stronger than S355M (450-610 MPa) due to normalization.
• Elongation: All provide ≥22%, supporting complex designs.
• Impact Toughness: S355NL’s -50°C toughness outperforms S355N and S355M (-20°C), making it ideal for cold climates.
• Hardness: S355M’s slightly lower hardness (140-180 HB vs 150-190 HB) reflects its thermomechanical processing for better formability.
• Thickness: All support up to 200 mm, versatile like en 10025 3 s355n normalized structural steel plate.

Processing and Fabrication

• S355N: Normalized for consistent microstructure; suited for standard welding. Preheating typically not required for <20 mm; optional for thicker plates (100-150°C); PWHT optional (550-650°C). CEV ≤0.43%.
• S355M: Thermomechanically rolled for enhanced formability; excellent weldability due to lower CEV (≤0.39%). Preheating rarely needed.
• S355NL: Normalized with lower impurities for superior toughness; similar welding to S355N. CEV ≤0.43%.

Consumables: All use ER70S-6 (GMAW) and EM12K flux with EH14 wire (SAW). S355M’s lower CEV enhances weld quality, similar to en 10025 3 s275n normalized structural steel plate.

Applications

• S355N: Bridges, cranes, and building frameworks in moderate climates (e.g., temperate Europe), leveraging 355 MPa yield strength.
• S355M: Complex structures like offshore platforms and wind towers, benefiting from enhanced formability and weldability.
• S355NL: Offshore platforms, wind towers, and bridges in cold climates (e.g., Arctic regions), relying on -50°C toughness.

S355NL is preferred for cold environments, S355M for formability, and S355N for cost-effective moderate-climate applications. For higher strength, consider en 10025 3 s460n normalized structural steel plate.

Key Differences Summarized

Why Choose Gangsteel?

Gangsteel supplies S355N, S355M, and S355NL:

• Inventory: Extensive stock in China.
• Sizes: Thickness 6–200 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 s355n normalized structural steel plate.

FAQ

What is the main difference in S355N, S355M, and S355NL?
S355N and S355NL are normalized (EN 10025-3) with -20°C and -50°C toughness, respectively; S355M is thermomechanically rolled (EN 10025-4) for better formability.

How does toughness compare for S355N, S355M, and S355NL?
S355NL’s -50°C toughness (≥27 J) outperforms S355N and S355M (-20°C), making it ideal for cold climates like Arctic regions.

Which is better for welding, S355N, S355M, or S355NL?
S355M’s lower CEV (≤0.39%) offers the best weldability, followed by S355N and S355NL (≤0.43%), with minimal preheating for thinner plates.

What applications suit S355N, S355M, and S355NL?
S355N suits moderate-climate bridges, S355M complex structures like offshore platforms, and S355NL cold-climate projects like wind towers.

How do costs compare for S355N, S355M, and S355NL?
S355M is 10-20% more expensive due to thermomechanical processing; S355N and S355NL have similar costs, more economical for general use.

What certifications support S355N, S355M, and S355NL?
Gangsteel provides all three with EN 10204 3.1/3.2, UT testing (EN 10160), and ABS/LR/BV/DNV approvals.

Summary

S355N, S355M, and S355NL are high-strength structural steels under EN 10025, each with 355 MPa yield strength but distinct processing and toughness profiles.

S355N and S355NL (EN 10025-3) are normalized for moderate (-20°C) and cold (-50°C) climates, respectively, while S355M (EN 10025-4) is thermomechanically rolled for enhanced formability in complex structures.

Gangsteel’s inventory supports thicknesses from 6–200 mm, with global delivery in 7-30 days and certifications like EN 10204 3.1/3.2.

S355NL excels in cold environments, S355M in formability, and S355N in cost-effective moderate-climate applications, offering tailored solutions for diverse structural needs.