S355NL/ML Enhanced Toughness

S355NL/ML Enhanced Toughness

S355NL ML, S355NL/ML, and S355NL/ML Z35 refer to high-strength, low-alloy structural steels under the EN 10025 standard, specifically designed for enhanced toughness in demanding applications. The designations typically indicate a comparison or combination of S355NL (EN 10025-3, normalized) and S355ML (EN 10025-4, thermomechanically rolled), with Z35 adding through-thickness quality for critical welds. This article explores the enhanced toughness properties of these grades, their chemical composition, mechanical properties, and applications, addressing core keywords s355nl ml, s355nl/ml, and s355nl/ml z35. For more details, visit our EN 10025-3 S355NL normalized structural steel plate.

Understanding 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.

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.

S355NL/ML Z35 likely refers to either S355NL or S355ML with Z35 quality (≥35% through-thickness reduction per EN 10164), though typically applied to S355NL for heavy welds. This article assumes S355NL ML and S355NL/ML indicate a comparison between S355NL and S355ML, focusing on their toughness.

Chemical Composition Comparison

The S355NL ML comparison highlights slight compositional differences:

Carbon Equivalent (CEV):

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

S355NL/ML shows S355ML’s lower carbon improves toughness and weldability.

Mechanical Properties and Enhanced Toughness

Both grades offer enhanced toughness at -50°C, with differences in processing:

• Toughness: Both achieve ≥27 J at -50°C, ideal for cold climates. S355ML’s TMCP may enhance grain consistency, potentially improving toughness in thinner sections. S355NL/ML Z35 (typically S355NL Z35) adds ≥35% through-thickness reduction, reducing lamellar tearing.
• Strength: Similar yield (355 MPa), but S355NL’s higher tensile range suits thicker sections.
• Thickness: S355NL up to 250 mm; S355ML up to 120 mm.

Welding and Heat Treatment

• S355NL: CEV ≤0.43%, preheating (100-150°C) for >20 mm; PWHT optional (550-650°C).
• S355ML: CEV ≤0.39%, less preheating (50-100°C).
• S355NL/ML Z35: Enhanced weld reliability with Z35 quality. Consumables: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).

Applications

• S355NL: Offshore platforms, wind towers, bridges (Z35 for heavy welds).
• S355ML: Similar applications, cost-effective for thinner sections.
• S355NL/ML Z35: Critical welded structures in cold climates.

Explore EN 10025-3 S420NL normalized structural steel plate.

Why Choose Gangsteel?

Gangsteel supplies S355NL ML:

• Inventory: Extensive stock in China.
• Sizes: Thickness 6–250 mm (S355NL), 6–120 mm (S355ML).
• Delivery: 7-30 days globally.
• Certifications: EN 10204 3.1/3.2, Z-test (EN 10164), UT testing (EN 10160).
• Processing: Cutting, welding, bending.

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

FAQ

What is S355NL ML?
S355NL ML refers to S355NL (normalized, -50°C toughness) and S355ML (TMCP, -50°C toughness) under EN 10025, both offering 355 MPa yield and enhanced toughness for cold-climate structures like offshore platforms.

What does S355NL/ML indicate?
S355NL/ML compares S355NL (normalized, up to 250 mm, tensile 470-630 MPa) and S355ML (TMCP, up to 120 mm, CEV ≤0.39%), both with ≥27 J at -50°C, suited for cold environments.

What is S355NL/ML Z35?
S355NL/ML Z35 typically refers to S355NL with Z35 quality (≥35% through-thickness reduction, EN 10164), ensuring resistance to lamellar tearing in heavy welded structures like wind towers.

How does S355NL ML toughness compare?
Both S355NL and S355ML achieve ≥27 J at -50°C, but S355ML’s TMCP may provide finer grains for enhanced toughness in thinner sections; S355NL is reliable for thicker plates.

Is S355NL/ML weldable?
Yes, S355NL (CEV ≤0.43%) and S355ML (CEV ≤0.39%) support GMAW/SAW, with S355ML needing less preheating, and Z35 ensuring weld integrity for critical applications.

What are applications of S355NL/ML Z35?
S355NL/ML Z35 is used in heavy welded structures like offshore platforms and bridges in cold climates, leveraging enhanced -50°C toughness and Z35 quality.