S355NL vs S355ML Performance

S355NL vs S355ML: Performance Comparison

S355NL vs S355ML and S355ML S355NL comparisons are essential for structural engineers selecting high-strength, low-alloy structural steels under the EN 10025 standard. S355NL, specified under EN 10025-3, is a normalized fine-grain steel optimized for low-temperature toughness, while S355ML, under EN 10025-4, is a thermomechanically rolled (TMCP) steel designed for enhanced formability and toughness in thinner sections. This article compares their performance in terms of chemical composition, mechanical properties, weldability, and applications, addressing core keywords s355nl vs s355ml and s355ml s355nl. For more details, visit our EN 10025-3 S355NL normalized structural steel plate.

Overview of S355NL and S355ML

S355NL (EN 10025-3)

S355NL is a normalized or normalized rolled fine-grain structural steel with:

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

It excels in cold climates and thicker sections, ideal for offshore platforms and bridges.

S355ML (EN 10025-4)

S355ML is a thermomechanically rolled (TMCP) fine-grain structural steel with:

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

S355ML is optimized for formability and thinner sections, suitable for cold-formed structures.

Chemical Composition Comparison

The S355NL vs S355ML comparison shows differences in composition affecting performance:

Carbon Equivalent (CEV):

• S355NL: ≤0.43% (≤63 mm).
• S355ML: ≤0.39% (≤40 mm).

Key Difference: S355ML’s lower carbon (0.14% vs 0.18%) and CEV (≤0.39%) enhance formability and weldability, while S355NL’s broader alloying supports robustness in thicker sections.

Mechanical Properties Comparison

The S355ML S355NL performance differs in strength, toughness, and thickness range:

• Strength: S355NL has a higher tensile strength range (470-630 MPa vs 450-610 MPa), but S355ML maintains higher yield strength in thicker sections due to TMCP.
• Toughness: Both achieve ≥27 J at -50°C, ensuring excellent low-temperature performance, though S355ML’s TMCP may provide slightly finer grains for consistent toughness in thinner sections.
• Hardness: S355ML’s slightly lower hardness (140-180 HB vs 150-190 HB) aids formability.
• Thickness Range: S355NL supports up to 250 mm, ideal for heavy structures; S355ML is limited to 120 mm, optimized for thinner, formed components.

Welding and Heat Treatment

• S355NL: CEV ≤0.43% supports GMAW or SAW (EN 1011-2). Preheating (100-150°C) for >20 mm; PWHT optional (550-650°C). Consumables: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).
• S355ML: Lower CEV (≤0.39%) reduces preheating (50-100°C for >10 mm), enhancing weldability for thinner sections. Same consumables.

Key Difference: S355ML’s lower CEV makes it more weldable, especially for thinner plates, while S355NL is reliable for thicker welds.

Applications

• S355NL:
  • Offshore platforms in cold marine environments (e.g., Arctic seas).
  • Wind towers in sub-zero climates (e.g., northern Europe).
  • Bridges and cranes in arctic regions.
    Its robustness across thick sections suits heavy-duty applications. See EN 10025-3 S355NL normalized structural steel plate.
• S355ML:
  • Cold-formed structural components (e.g., beams, profiles).
  • Automotive and machinery parts in cold climates.
  • Lightweight structures requiring formability.
    Its TMCP enhances formability for thinner sections.

The S355NL vs S355ML application difference highlights S355NL’s strength in thick, cold-climate structures and S355ML’s advantage in formable, thinner components.

Which is Better: S355NL or S355ML?

• Choose S355NLfor:
  • Thick sections (up to 250 mm) in extreme cold (-50°C).
  • Heavy-duty structures like offshore platforms and bridges.
  • Applications requiring higher tensile strength (470-630 MPa).
• Choose S355MLfor:
  • Thinner sections (≤120 mm) requiring cold forming.
  • Lightweight structures or components with enhanced weldability.
  • Cost-effective fabrication in cold climates with less thickness.

The S355ML S355NL choice depends on thickness, formability, and project requirements.

Equivalent Grades

• S355NL: ASTM A633 Grade E, Q345E (China), TStE 355 (DIN).
• S355ML: ASTM A1011 HSLAS-F Grade 50, Q355MC (China).

Explore EN 10025-3 S420NL normalized structural steel plate.

Why Choose Gangsteel?

Gangsteel supplies both grades:

• Inventory: Extensive stock in China.
• Sizes: S355NL (6–250 mm), S355ML (1.5–120 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, forming (S355ML).

Contact us for EN 10025-3 S355NL normalized structural steel plate.

FAQ

What is the main difference in S355NL vs S355ML?
S355NL is normalized, ideal for thick sections (up to 250 mm) with tensile strength 470-630 MPa, while S355ML is TMCP, optimized for thinner sections (≤120 mm) with better formability and CEV ≤0.39%. Both have -50°C toughness.

Which is better for cold climates in S355ML S355NL?
Both S355NL and S355ML offer ≥27 J at -50°C, but S355NL is better for thicker, heavy-duty structures in cold climates, while S355ML suits thinner, cold-formed components.

How does weldability compare in S355NL vs S355ML?
S355ML’s lower CEV (≤0.39% vs ≤0.43%) requires less preheating (50-100°C vs 100-150°C), making it more weldable for thinner sections; S355NL is reliable for thicker welds.

What are applications of S355ML S355NL?
S355NL is used in thick offshore platforms and bridges in cold climates; S355ML in cold-formed profiles and automotive parts, leveraging formability.

Which is more formable in S355NL vs S355ML?
S355ML is more formable due to its TMCP process and lower carbon (0.14% vs 0.18%), ideal for cold-formed components, while S355NL prioritizes toughness for thicker structures.

Can S355ML replace S355NL?
S355ML can replace S355NL in thinner sections (≤120 mm) for cold climates with forming needs, but not for thicker, heavy-duty structures due to S355NL’s wider thickness range.