S355NL Yield Strength Details

 

 

 

S355NL Yield Strength Details

S355NL yield strength is a defining characteristic of this high-strength, low-alloy structural steel under EN 10025-3, specifying normalized or normalized rolled weldable fine grain structural steels. With a minimum yield strength of 355 MPa for thicknesses up to 16 mm, S355NL is designed for applications requiring robust load-bearing capacity in cold climates, such as offshore platforms and bridges.

This article provides detailed insights into the S355NL yield strength, its variation with thickness, chemical composition, mechanical properties, and applications, addressing the core keyword s355nl yield strength. For more details, visit our EN 10025-3 S355NL normalized structural steel plate.

 

What is S355NL Steel?

S355NL is a fine-grain structural steel under EN 10025-3, optimized for high strength and low-temperature toughness. Its designation indicates:

• S: Structural steel.
• 355: Minimum yield strength of 355 MPa (≤16 mm).
• NL: Normalized or normalized rolled, with impact toughness tested at -50°C.

The S355NL yield strength ensures its suitability for high-stress structural applications in cold environments.

 

S355NL Yield Strength Details

The S355NL yield strength varies with thickness, reflecting the steel’s ability to resist deformation under load. As per EN 10025-3, the minimum yield strength is specified as follows:

Thickness (mm)	Yield Strength (min, MPa)	Tensile Strength (MPa)	Elongation (min, %)	Impact Energy (min, J @ -50°C)
≤16	355	470-630	22	27
16<t≤40	345	470-630	22	27
40<t≤63	335	470-630	22	27
63<t≤80	325	470-630	21	27
80<t≤100	305	470-630	21	27
100<t≤150	285	450-610	21	27
150<t≤200	265	450-610	21	27
200<t≤250	245	450-610	21	27

Key Points on Yield Strength

• Definition: Yield strength is the stress at which a material begins to deform plastically, critical for structural components under load. For S355NL, it ranges from 355 MPa (≤16 mm) to 245 MPa (200-250 mm).
• Thickness Variation: The yield strength decreases with increasing thickness due to slower cooling rates during normalization, which slightly coarsens the grain structure. However, the fine-grain microstructure ensures consistent performance.
• Applications: The high S355NL yield strength supports load-bearing structures like bridge girders and wind tower bases, maintaining integrity under heavy static and dynamic loads.

 

Chemical Composition Supporting Yield Strength

The chemical composition of S355NL underpins its yield strength:

Element	Ladle Analysis (max %)	Product Analysis (max %)
Carbon (C)	0.18	0.20
Silicon (Si)	0.50	0.55
Manganese (Mn)	0.90-1.65	0.85-1.75
Phosphorus (P)	0.025	0.035
Sulfur (S)	0.015	0.025
Nitrogen (N)	0.015	0.017
Aluminum (Al)	0.020 (min, total)	0.015 (min, total)
Niobium (Nb)	0.05	0.06
Vanadium (V)	0.12	0.15
Titanium (Ti)	0.05	0.06
Chromium (Cr)	0.30	0.35
Nickel (Ni)	0.30	0.35
Molybdenum (Mo)	0.10	0.13
Copper (Cu)	0.55	0.60

Key Elements:

• Manganese (Mn): 0.90-1.65% enhances S355NL yield strength by strengthening the steel matrix.
• Low Carbon (C): ≤0.18% maintains toughness while supporting strength.
• Niobium (Nb), Vanadium (V): Microalloying elements refine grains, contributing to high yield strength and toughness.
• Carbon Equivalent (CEV): ≤0.43% (≤63 mm), calculated as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, ensures weldability.

 

Mechanical Properties Complementing Yield Strength

The S355NL yield strength is complemented by:

• Tensile Strength: 470-630 MPa (≤100 mm), dropping to 450-610 MPa for thicker plates, ensuring durability under tension.
• Elongation: ≥22% (≤63 mm), allowing ductility for complex designs.
• Impact Toughness: ≥27 J at -50°C, critical for cold-climate reliability, supporting the yield strength in dynamic load conditions.

 

Welding and Heat Treatment

S355NL supports welding without compromising S355NL yield strength:

• Welding: Compatible with GMAW and SAW per EN 1011-2. Preheating (100-150°C) for >20 mm; no preheat for thinner plates.
• PWHT: Optional at 550-650°C for critical welds.
• Consumables: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).

The fine-grain structure ensures weld integrity, maintaining strength.

 

Applications

The S355NL yield strength supports applications in:

• Offshore Platforms: Resists heavy loads in cold marine environments.
• Wind Turbine Towers: Supports sub-zero structural demands.
• Bridges and Cranes: Load-bearing components in northern climates.
• Pressure Vessels: Low-temperature storage systems.

Explore related grades like EN 10025-3 S420NL normalized structural steel plate.

 

Equivalent Grades

Standard	Equivalent Grade	Notes
EN 10025-4	S355M	Thermomechanically rolled, -50°C toughness.
EN 10025-3	S355N	-20°C toughness, less cold-tolerant.
DIN	TStE 355	Similar strength and toughness.
GB (China)	Q345E	-40°C toughness, close match.
ASTM/ASME	A633 Grade E	-40°C toughness, yield ~415 MPa.

See EN 10025-3 S355N normalized structural steel plate.

 

Why Choose Gangsteel?

Gangsteel supplies S355NL:

• Inventory: Extensive stock in China.
• Sizes: Thickness 6–250 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 S355NL normalized structural steel plate.

 

FAQ

What is the S355NL yield strength?
S355NL yield strength is ≥355 MPa for thicknesses ≤16 mm, decreasing to 245 MPa for 200-250 mm, ensuring robust load-bearing capacity for structures like bridges and offshore platforms.

How does S355NL yield strengthvary with thickness?
The S355NL yield strength decreases from 355 MPa (≤16 mm) to 245 MPa (200-250 mm) due to slower cooling in thicker plates, yet maintains consistent toughness and strength for structural applications.

What supports the S355NL yield strength?
Manganese (0.90-1.65%) and microalloying elements (Nb, V) in the S355NL composition, combined with normalization, refine the grain structure to achieve high yield strength and -50°C toughness.

Is S355NLweldable with its yield strength?
Yes, S355NL’s CEV ≤0.43% supports GMAW/SAW welding with minimal preheating (100-150°C for >20 mm), maintaining yield strength in welded structures like wind towers.

What are applications of S355NL yield strength?
The S355NL yield strength supports offshore platforms, wind towers, bridges, and pressure vessels in cold climates, ensuring structural integrity under heavy loads.

How does S355NLcompare to S355J2?
S355NL has similar yield strength (355 MPa) but is normalized, tested at -50°C for cold climates; S355J2 is hot-rolled, tested at -20°C, suited for temperate regions.