s355nl astm equivalent astm a572 gr 65

S355NL ASTM Equivalent: Is ASTM A572 Grade 65 the Best Match?

EN 10025-3 S355NL is a high-strength, fine-grained structural steel designed for low-temperature applications, offering excellent toughness and weldability. A common question is whether ASTM A572 Grade 65 is its closest ASTM equivalent. This article compares their chemical composition, mechanical properties, welding characteristics, and applications to evaluate the equivalence. For more details, explore our EN 10025-3 S355NL normalized structural steel plate.

Overview of S355NL and ASTM A572 Grade 65

S355NL (EN 10025-3)

S355NL is a normalized or normalized rolled fine grain structural steel under EN 10025-3. Its designation indicates:

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

It’s ideal for cold climates, such as offshore platforms and bridges, due to its fine grain structure and low-temperature toughness.

ASTM A572 Grade 65

ASTM A572 Grade 65 is a high-strength low-alloy (HSLA) structural steel under ASTM A572/A572M, typically supplied in hot-rolled condition. It’s designed for structural applications like buildings and bridges, with a focus on strength and moderate toughness. The “Grade 65” refers to a minimum yield strength of 65 ksi (approximately 448 MPa).

Chemical Composition Comparison

The chemical compositions of S355NL and ASTM A572 Grade 65 show similarities but differ in grain-refining elements and impurity controls, reflecting their distinct standards.

Carbon Equivalent (CEV):

• S355NL: ≤0.43% (≤63 mm), calculated as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, ensuring excellent weldability due to fine grain control.
• A572 Gr 65: ≤0.47% (typical), slightly higher due to looser controls on impurities, but still weldable.

S355NL’s stricter limits on phosphorus, sulfur, and nitrogen, plus mandatory aluminum for grain refinement, enhance its low-temperature toughness and weldability compared to A572 Grade 65.

Mechanical Properties Comparison

While both steels have comparable strength, their toughness and testing conditions differ significantly.

Key Differences:

• Strength: A572 Grade 65 has a higher minimum yield strength (448 MPa vs 355 MPa), making it stronger but potentially less ductile.
• Toughness: S355NL guarantees impact toughness at -50°C, ideal for cold climates, while A572 Grade 65’s toughness is typically tested at 0°C (if specified), limiting its use in extreme cold.
• Thickness Range: S355NL supports up to 250 mm with consistent low-temp properties; A572 Grade 65 is typically specified up to 100 mm.

Welding and Heat Treatment

• S355NL: Its low CEV (≤0.43%) and fine grain structure ensure excellent weldability using GMAW or SAW. Preheating (100-150°C) is advised for >20 mm thicknesses; post-weld heat treatment (PWHT) at 550-650°C is optional for critical welds. Recommended fillers: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).
• A572 Gr 65: CEV ≤0.47% supports weldability, but higher carbon and impurities may require more preheating (125-175°C for >25 mm). PWHT is rarely needed. Similar fillers apply.

S355NL’s finer grain and lower CEV reduce welding imperfections compared to A572 Grade 65.

Applications

• S355NL: Suited for low-temperature environments:
  • Offshore platforms and wind towers in cold climates.
  • Bridges and cranes in northern regions.
  • Pressure vessels for low-temperature storage. Its -50°C toughness ensures reliability in harsh conditions. See EN 10025-3 S355NL normalized structural steel plate.
• A572 Gr 65: Used in general structural applications:
  • High-rise buildings and bridges in temperate climates.
  • Heavy machinery and equipment frames.
  • Construction where higher strength is prioritized over cold toughness.

A572 Grade 65’s higher strength suits weight-optimized designs, but S355NL is better for sub-zero conditions.

Is ASTM A572 Grade 65 the Best ASTM Equivalent?

ASTM A572 Grade 65 is a close equivalent to S355NL due to its high strength and similar alloying, but it’s not a perfect match:

• Strength: A572 Grade 65’s higher yield (448 MPa vs 355 MPa) makes it stronger, but this may require design adjustments.
• Toughness: S355NL’s -50°C impact testing surpasses A572 Grade 65’s optional 0°C testing, making S355NL better for cold environments.
• Normalization: S355NL’s mandatory normalization ensures finer grains and consistent low-temp performance; A572 Grade 65 is typically hot-rolled, with less focus on grain refinement.

Alternative ASTM Equivalents:

• ASTM A633 Grade E: Closer in low-temperature toughness (tested at -40°C) but slightly lower yield (~415 MPa).
• ASTM A709 Grade 50W: Matches S355NL’s toughness better but has lower strength (~345 MPa).

For related grades, explore EN 10025-3 S420NL normalized structural steel plate or EN 10025-3 S355N normalized structural steel plate.

Why Choose Gangsteel for S355NL?

Gangsteel offers high-quality S355NL:

• Inventory: Extensive stock in China for S355NL and similar grades.
• 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

Is ASTM A572 Grade 65 a direct equivalent to S355NL?No; it’s close in strength but lacks S355NL’s -50°C toughness and fine-grain normalization.

Which is better for cold climates?S355NL, due to its guaranteed -50°C impact toughness, outperforms A572 Grade 65 (0°C if tested).

Can S355NL and A572 Grade 65 be welded similarly?Yes, but S355NL’s lower CEV (≤0.43% vs ≤0.47%) reduces preheating needs (100-150°C vs 125-175°C for thicker plates).

What are the main applications of S355NL vs A572 Gr 65?S355NL: Cold-region offshore platforms, wind towers. A572 Gr 65: General buildings, bridges in milder climates.

Can A572 Grade 65 replace S355NL?Only in non-critical cold environments; S355NL’s low-temp toughness is superior.

What other ASTM grades are close to S355NL?A633 Grade E (better toughness match) or A709 Grade 50W (weathering properties).

How does S355NL compare to S355J2?S355NL is normalized fine-grain for -50°C, while S355J2 is hot-rolled for -20°C. See EN 10025-3 S355NL normalized structural steel plate.

Explore related grades like EN 10025-3 S460NL normalized structural steel plate.