What is the difference between S420NL and S420N?

As a premier exporter and manufacturer of high-quality structural steel plates, Gangsteel specializes in producing EN 10025-3 compliant materials, including the versatile S420N and S420NL steel grades.

Both S420N and S420NL are normalized fine-grain structural steels designed for welded constructions requiring enhanced toughness at low temperatures.

Ideal for heavy-duty applications in bridges, cranes, and offshore structures, our S420N and S420NL 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.

Overview of S420N and S420NL

S420N (material no. 1.8902) and S420NL (1.8912) are high-strength low-alloy (HSLA) fine-grain structural steels under EN 10025-3, with "N" indicating normalized delivery. The key difference is the impact test temperature: S420N at -20°C (40 J min longitudinal), S420NL at -50°C (27 J min). This makes S420NL suitable for arctic environments, while S420N suffices for moderate cold. Both share identical yield (420 MPa ≤16 mm) and tensile strength, with fine-grain structure for ductility.

Gangsteel produces both in thicknesses up to 250 mm, with dual certifications available.

Chemical Composition Comparison

Both grades have identical low-carbon profiles for weldability (ladle analysis, max % unless noted, ≤100 mm thickness).

*Note: Identical compositions ensure similar weldability (CEV ≤0.48); no preheat ≤50 mm.

Mechanical Properties Comparison

Both grades are normalized for fine-grain structure, with identical properties except impact temperature (minimum values).

*Notes: Elongation per Lo = 5.65 √So. S420NL's lower impact values at -50°C still provide superior cold performance than S420N at equivalent temperatures.

Heat Treatment Guide for S420N and S420NL Steel

Both grades are supplied in normalized (+N) condition, refining grain for toughness.

Normalization Process

• Heating Temperature: Austenitize at 880–920°C (uniform).
• Soaking Time: 1 hour per 25 mm thickness, min 30 minutes.
• Cooling: Air cool controlled rate.
• Purpose: Enhances ductility, meets mechanical specs.

Re-normalize post-forming if needed. Avoid quenching.

Welding Guidelines

• Preheating: Not required ≤50 mm; 100–150°C for thicker (CEV ≤0.48).
• Interpass Temp: Max 200°C.
• PWHT: Optional 550–650°C stress-relief.
• Hot Forming: >850°C; re-normalize if <720°C.

Follow EN 1011-2. Gangsteel optimizes for minimal heat treatment.

Applications of S420N and S420NL Steel

Both for heavy engineering, infrastructure, construction in cold climates. S420NL preferred for extreme cold like arctic offshore.

Equivalent Grades

Why Choose Gangsteel?

With state-of-the-art mills and ISO-certified quality, Gangsteel delivers S420N and S420NL 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 s420nl normalized structural steel plate product page or contact our sales team today.

Summary

S420N and S420NL are EN 10025-3 normalized fine-grain steels with identical 420 MPa yield and 520–680 MPa tensile, but differ in impact: S420N 40 J at -20°C vs S420NL 27 J at -50°C, making S420NL better for extreme cold. Both excel in cold welded structures like bridges and offshore platforms. S420N and S420NL from Gangsteel ensure reliability with certified plates for optimal performance.

FAQ

What is the main difference between S420N and S420NL?

The primary distinction is the Charpy V-notch impact testing temperature: S420N requires a minimum of 40 J longitudinal at -20°C, while S420NL demands 27 J at -50°C. This makes S420NL more suitable for sub-zero environments, as it guarantees toughness in colder conditions without altering other mechanical properties like yield or tensile strength.

Are the chemical compositions of S420N and S420NL identical?

Yes, S420N and S420NL share the same chemical composition, including maximum carbon at 0.20%, manganese at 1.00–1.70%, and CEV ≤0.48. This ensures low hardenability and resistance to cracking, with aluminum or niobium for grain refinement in both grades.

Do S420N and S420NL have the same mechanical properties besides impact testing?

Yes, for thicknesses up to 250 mm, both exhibit the same minimum yield strength (decreasing from 420 MPa at ≤16 mm to 340 MPa at 200–250 mm), tensile strength (520–680 MPa up to 100 mm, 500–650 MPa beyond), and elongation (18–19%). The normalization process ensures a fine-grain structure in both, but S420NL's lower impact values at -50°C still provide better overall cold performance than S420N at equivalent temperatures.

In what applications should I choose S420N over S420NL?

Opt for S420N in moderate climates or non-critical low-temp structures, such as indoor machinery, standard bridges, or building frameworks where temperatures rarely drop below -20°C. It's more economical while meeting EN 10025-3 standards for weldable fine-grain steel, saving costs without compromising strength in temperate zones.

When is S420NL necessary, and what are its advantages in cold environments?

S420NL is essential for applications exposed to -50°C or lower, like offshore oil rigs, arctic pipelines, northern cranes, or wind farm foundations, where brittle fracture risks increase. Its advantages include superior ductility and impact resistance in extreme cold—maintaining 27 J at -50°C versus S420N's potential drop-off—leading to higher safety margins, reduced failure rates, and compliance with stringent codes like Eurocode 3 for cold regions.

Can S420N and S420NL be welded similarly?

Absolutely; both have low CEV (≤0.48) for excellent weldability without preheating up to 50 mm thickness. Use matching low-hydrogen electrodes (e.g., E9018) and limit interpass temperatures to 200°C. For S420NL in cold service, post-weld stress relief at 550–650°C may be recommended more often to preserve toughness, but procedures per EN 1011-2 apply to both.

What are the equivalent grades for S420N and S420NL?

S420N equivalents include DIN TStE 420 and ASTM A572 Gr. 65; S420NL aligns with DIN TStE 420 L and ASTM A633 Gr. C. Both share JIS SM570. Always verify impact equivalence for substitutions, as S420NL's -50°C rating may require normalized delivery in equivalents.