S355NL Chemical Composition Explained

S355NL Chemical Composition Explained

S355NL chemical composition is a critical factor defining the performance of this high-strength, low-alloy structural steel under EN 10025-3, which specifies normalized or normalized rolled weldable fine grain structural steels.

The carefully controlled S355NL composition ensures excellent weldability, toughness, and strength, making it ideal for applications in cold climates like offshore platforms and bridges. This article explains the chemical makeup of S355NL, its impact on S355NL material properties, and how it supports structural applications, addressing core keywords s355nl chemical composition, s355nl composition, and s355nl material properties.

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, designed for high strength and low-temperature performance. Its designation indicates:

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

The S355NL chemical composition is tailored to achieve a refined microstructure, enhancing toughness and weldability for demanding environments.

Chemical Composition of S355NL

The S355NL composition is strictly controlled to balance strength, toughness, and weldability. Below is the detailed chemical composition (ladle and product analysis) per EN 10025-3:

Key Elements and Their Roles

• Carbon (C): Low content (≤0.18%) minimizes hardness, enhancing weldability and toughness.
• Manganese (Mn): Boosts strength and toughness; range (0.90-1.65%) ensures structural integrity.
• Phosphorus (P) and Sulfur (S): Low levels (≤0.025% and ≤0.015%) reduce brittleness and improve weld quality.
• Aluminum (Al): Minimum 0.02% promotes fine grain structure, enhancing low-temperature toughness.
• Niobium (Nb) and Vanadium (V): Microalloying elements refine grain size, improving strength and toughness.

The Carbon Equivalent (CEV), calculated as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, is ≤0.43% for thicknesses ≤63 mm. This low CEV ensures the S355NL material properties support efficient welding with minimal risk of cold cracking.

Impact on S355NL Material Properties

The S355NL chemical composition directly influences its S355NL material properties:

• Strength: Controlled carbon and manganese levels achieve a minimum yield strength of 355 MPa and tensile strength of 470-630 MPa.
• Toughness: Low sulfur, phosphorus, and nitrogen, combined with grain-refining elements (Al, Nb, V), ensure ≥27 J impact energy at -50°C, ideal for cold climates.
• Weldability: Low CEV (≤0.43%) minimizes welding-induced stresses, supporting standard processes like GMAW and SAW.
• Ductility: Fine grain structure enhances elongation (≥22%), allowing flexibility in structural designs.

These properties make S355NL suitable for high-stress, low-temperature applications.

Mechanical Properties Overview

To contextualize the impact of the S355NL composition, here are its key mechanical properties:

These properties, driven by the S355NL chemical composition, ensure reliability in demanding environments.

Welding and Heat Treatment

The S355NL material properties include excellent weldability due to its low CEV (≤0.43%):

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

The low carbon and impurity levels in the S355NL composition reduce weld imperfections.

Applications of S355NL

The S355NL material properties make it ideal for:

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

Its Eurocode 3 compliance ensures safety in structural designs. Explore related grades like EN 10025-3 S420NL normalized structural steel plate.

Equivalent Grades

The S355NL chemical composition aligns with:

See EN 10025-3 S355N normalized structural steel plate.

Why Choose Gangsteel for S355NL?

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 defines the S355NL chemical composition?
Low carbon (≤0.18%), manganese (0.90-1.65%), and grain-refining elements (Al, Nb, V) for toughness and weldability.

How does S355NL composition affect properties?
Ensures 355 MPa yield, -50°C toughness, and excellent weldability (CEV ≤0.43%).

What are S355NL material properties?
High strength, low-temp toughness (≥27 J at -50°C), and good ductility (≥22% elongation).

Is S355NL weldable?
Yes; low CEV supports GMAW/SAW with minimal preheating.

What are applications of S355NL?
Offshore platforms, wind towers, and cold-region bridges.

What is the ASTM equivalent?
A633 Grade E for toughness, A572 Grade 65 for strength. See EN 10025-3 S275N normalized structural steel plate.