S355N vs S355M Steel Comparison

S355N vs S355M Steel Comparison

At Gangsteel, we’re here to clarify the differences between S355N vs S355M, two high-strength, low-alloy structural steels under the EN 10025 standard, each designed for specific structural applications. S355N, under EN 10025-3, is a normalized or normalized rolled steel with 355 MPa yield strength and -20°C toughness, ideal for moderate climates. S355M, under EN 10025-4, is a thermomechanically rolled steel with similar strength but enhanced formability, suited for complex structures.

As part of the en 10025 3 normalized steel plate and EN 10025-4 families, these grades serve distinct purposes. 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 and S355M

• S355N (EN 10025-3, 1.0545): A normalized or normalized rolled fine-grain steel with 355 MPa yield strength and -20°C toughness, designed for high-load applications like bridges and cranes in moderate climates.
• S355M (EN 10025-4, 1.8823): A thermomechanically rolled fine-grain steel with 355 MPa yield strength and -20°C toughness, optimized for enhanced formability in complex structures like offshore platforms.

S355N offers robust toughness for standard structural applications, while S355M’s thermomechanical processing enhances formability and weldability for intricate designs.

Chemical Composition Comparison

The chemical composition of S355N vs S355M influences their properties:

Carbon Equivalent (CEV):

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

S355M’s lower carbon (0.14% vs 0.20%), sulfur (0.020% vs 0.025%), phosphorus (0.025% vs 0.030%), and nitrogen (0.015% vs 0.025%) enhance weldability and formability, while S355N’s composition supports robust toughness, similar to en 10025 3 s420n normalized structural steel plate.

Mechanical Properties Comparison

S355N vs S355M mechanical properties highlight their differences:

• Yield Strength: Both offer 355 MPa, ideal for moderate-load structures.
• Tensile Strength: S355N’s 470-630 MPa slightly exceeds S355M’s 450-610 MPa, reflecting normalized processing.
• Elongation: Both provide ≥22%, supporting complex designs.
• Impact Toughness: Both offer ≥27 J at -20°C, suitable for moderate climates.
• Hardness: S355M’s slightly lower hardness (140-180 HB vs 150-190 HB) reflects its thermomechanical processing for better formability.
• Thickness: Both support up to 200 mm, versatile like en 10025 3 s355n normalized structural steel plate.

Processing and Fabrication

• S355N: Normalized for consistent microstructure, enhancing toughness for standard welds. 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 and weldability; lower CEV (≤0.39%) reduces preheating needs.

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

Applications

• S355N: Used in high-load structures like bridges, cranes, and building frameworks in moderate climates, leveraging its fine-grain structure and toughness.
• S355M: Suited for complex structures like offshore platforms and wind towers, benefiting from enhanced formability and weldability.

S355N is preferred for standard high-strength applications, while S355M excels in projects requiring intricate forming. For colder climates, consider en 10025 3 s355nl normalized structural steel plate.

Key Differences Summarized

Why Choose Gangsteel?

Gangsteel supplies S355N and S355M:

• Inventory: Extensive stock in China.
• Sizes: Thicknesses 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 vs S355M?
S355N is normalized for robust toughness in standard applications, while S355M is thermomechanically rolled for enhanced formability in complex structures.

How do S355N and S355M toughness compare?
Both offer ≥27 J at -20°C, but S355M’s lower CEV (≤0.39%) and impurities enhance weldability and formability.

Which is better for welding, S355N or S355M?
S355M’s lower CEV (≤0.39% vs ≤0.43%) and reduced carbon/sulfur/phosphorus make it easier to weld, especially for complex designs.

What applications suit S355N vs S355M?
S355N is ideal for bridges and cranes in moderate climates; S355M suits offshore platforms and wind towers requiring formability.

How do S355N and S355M costs compare?
S355M is 10-20% more expensive than S355N due to thermomechanical processing.

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

Summary

S355N and S355M are high-strength, low-alloy structural steels under EN 10025, both offering 355 MPa yield strength and -20°C toughness (≥27 J).

S355N (EN 10025-3) is normalized for robust toughness in bridges and cranes, while S355M (EN 10025-4) is thermomechanically rolled for enhanced formability in complex structures like offshore platforms.

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.

S355N offers cost-effective toughness, while S355M excels in formability, providing tailored solutions for diverse structural needs.