S275NL Steel Mechanical Properties and Heat Treatment Guide

S275NL Steel | Mechanical Properties and Heat Treatment Guide

As a premier exporter and manufacturer of high-quality structural steel plates, Gangsteel specializes in producing EN 10025-3 compliant materials, including the versatile S275NL steel grade.

S275NL is a normalized fine-grain structural steel designed for welded constructions requiring enhanced toughness at low temperatures, down to -50°C.

Ideal for heavy-duty applications in bridges, cranes, and offshore structures, our S275NL plates are delivered in normalized or normalized rolled conditions to ensure superior weldability and impact resistance.

For a comprehensive overview of our en 10025 3 normalized steel plate offerings, explore our full range.

What is S275NL Steel?

S275NL steel, designated as 1.0491 under the European standard EN 10025-3, belongs to the family of weldable fine-grain steels. The "NL" suffix indicates its suitability for normalized delivery with a minimum impact energy of 27 Joules at -50°C in the longitudinal direction, making it perfect for cold climates and demanding environments. Compared to similar grades like en 10025 3 s275n normalized structural steel plate, S275NL offers improved low-temperature performance without compromising on strength.

Gangsteel produces S275NL plates in thicknesses up to 250 mm, with precise control over chemical composition to meet CEV limits for optimal weldability. Our plates are rigorously tested to comply with international standards, ensuring reliability for global projects.

Chemical Composition of S275NL Steel

The chemical makeup of S275NL is carefully balanced to provide excellent strength, ductility, and resistance to brittle fracture. Below is the product analysis for nominal thicknesses ≤ 100 mm, with a maximum Carbon Equivalent Value (CEV) of 0.40 (or up to 0.42 in some specifications).

*Note: For long products, P and S may be 0.005% higher. If N-binding elements are present, the Al minimum does not apply. Cu above 0.4% may affect hot forming.

This low carbon and controlled alloying ensure minimal risk of cracking during welding.

Mechanical Properties of S275NL Steel

S275NL exhibits robust mechanical characteristics, with properties varying by thickness to accommodate diverse fabrication needs. All values are for normalized (+N) condition. The table below consolidates yield strength, tensile strength, elongation, and Charpy V-Notch impact energy (longitudinal and transverse at key temperatures, with focus on -50°C minimums).

*Notes: Elongation based on Lo = 5.65 √So. Impact values are minimums; higher at warmer temperatures (e.g., longitudinal at 20°C: 63 J). These properties position S275NL as a cost-effective choice for structures needing high toughness, outperforming standard S275JR in sub-zero conditions.

Heat Treatment Guide for S275NL Steel

S275NL steel is primarily supplied in the normalized (+N) or normalized rolled condition as per EN 10025-3, which refines the grain structure for improved toughness and weldability. Normalization is essential to achieve the fine-grain microstructure required for low-temperature impact resistance.

Normalization Process

• Heating Temperature: Austenitize at 880–920°C (uniform throughout the thickness).
• Soaking Time: Hold for approximately 1 hour per 25 mm of thickness, minimum 30 minutes.
• Cooling: Air cool to room temperature at a controlled rate to avoid excessive hardening.
• Purpose: Refines ferrite-pearlite structure, enhances ductility, and ensures compliance with mechanical properties post-delivery.

If post-delivery heat treatment is needed (e.g., after hot forming), re-normalize to maintain properties. Avoid quenching unless specified, as it may alter toughness.

Welding Heat Treatment Guidelines

• Preheating: Not required for thicknesses ≤ 40 mm; recommend 50–100°C for thicker sections (>40 mm) to prevent cold cracking, based on CEV ≤ 0.42.
• Interpass Temperature: Maximum 200°C to preserve fine grain.
• Post-Weld Heat Treatment (PWHT): Optional stress-relief at 550–650°C for 1 hour per 25 mm thickness, followed by slow cooling. Not typically needed due to low hardenability.
• Hot Forming: Perform above 850°C; re-normalize if forming temperature drops below 720°C.

Always consult EN 1011-2 for welding recommendations. Gangsteel provides plates optimized for these processes to minimize heat treatment needs.

Applications of S275NL Steel Plates

S275NL is widely used in:

• Heavy Engineering: Cranes, earthmoving equipment, and load-bearing frameworks.
• Infrastructure: Bridges, viaducts, and offshore platforms where low-temperature ductility is critical.
• Construction: Welded structures in shipbuilding and pressure vessels.

For higher strength needs, consider upgrading to en 10025 3 s355nl normalized structural steel plate or en 10025 3 s420nl normalized structural steel plate.

Equivalent Grades to S275NL

Why Choose Gangsteel for S275NL Steel?

With state-of-the-art mills and a commitment to ISO-certified quality, Gangsteel delivers S275NL plates tailored to your specifications. Stocked in various sizes and ready for immediate export worldwide. For detailed pricing and availability, visit our en 10025 3 s275nl normalized structural steel plate product page or contact our sales team today.

Summary

S275NL steel from EN 10025-3 provides balanced mechanical properties with yield strengths from 205–275 MPa, excellent elongation, and superior impact toughness at -50°C, all optimized through normalization heat treatment. Ideal for weldable structures in harsh environments, Gangsteel's S275NL plates ensure reliability with guided heat treatment practices for seamless fabrication.

FAQ

What is the normalization temperature for S275NL?

Austenitizing occurs at 880–920°C, followed by air cooling to achieve the fine-grain structure specified in EN 10025-3.

Does S275NL require preheating for welding?

Generally no for thin sections; use 50–100°C preheat for thicknesses over 40 mm to mitigate cracking risks.

How does heat treatment affect S275NL's mechanical properties?

Normalization refines the microstructure, maintaining yield, tensile, and impact values as per the standard tables.

What is the maximum thickness for full mechanical properties in S275NL?

Up to 250 mm, with adjusted minimum yields for thicker plates to ensure performance.

Can S275NL undergo quenching and tempering?

It supports Q&T, but normalization is standard; consult for custom heat treatments to retain low-temperature toughness.