S355ML vs S355NL is a common comparison in structural steel selection, as both grades are high-strength, low-alloy steels under the EN 10025 standard but differ in processing and performance. S355NL, specified under EN 10025-3, is a normalized fine-grain steel, while S355ML, under EN 10025-4, is thermomechanically rolled (TMCP).
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℃ for low-temperature applications.
Its normalization process ensures a refined microstructure, ideal for cold climates like offshore platforms.
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℃.
TMCP produces finer grains, enhancing strength and weldability, often at a lower cost than normalization.
|
|
S355NL (EN 10025-3, Ladle, max %) |
S355ML (EN 10025-4, Ladle, max %) |
|---|---|---|
|
0.18 |
0.14 |
|
|
0.50 |
0.50 |
|
|
0.90-1.65 |
1.60 |
|
|
0.025 |
0.025 |
|
|
0.015 |
0.020 |
|
|
0.015 |
0.015 |
|
|
0.02 (min, total) |
0.02 (min, total) |
|
|
0.05 |
0.05 |
|
|
0.12 |
0.10 |
|
|
0.05 |
0.05 |
|
|
0.30 |
0.30 |
|
|
0.30 |
0.30 |
|
|
0.10 |
0.20 |
|
|
0.55 |
0.55 |
|
|
S355NL (EN 10025-3) |
S355ML (EN 10025-4) |
|---|---|---|
|
|
||
|
<=16 mm |
355 |
355 |
|
16 |
345 |
355 |
|
40 |
335 |
345 |
|
|
470-630 |
450-610 |
|
|
22 (<=63 mm) |
22 (<=40 mm) |
|
|
27 @ -50℃ (longitudinal) |
27 @ -50℃ (longitudinal) |
S355NL: CEV ≤0.43% supports GMAW or SAW (EN 1011-2). Preheating (100-150°C) for >20 mm; PWHT (550-650℃) optional. Consumables: ER70S-6 (GMAW), EM12K flux with EH14 wire (SAW).
S355ML: Lower CEV (≤0.39%) enhances weldability, often requiring less preheating (50-100°C for >20 mm). Same consumables apply.
The S355NL vs S355ML welding comparison favors S355ML for cost-efficient fabrication due to its TMCP process.
S355NL:
Offshore platforms in cold marine environments.
Wind towers in sub-zero climates.
Bridges and cranes in northern regions.
Its normalization ensures reliability across a wide thickness range (up to 250 mm).
S355ML:
Similar applications (offshore, wind towers, bridges) but preferred in projects prioritizing weldability and cost.
Limited to thinner sections (<=120 mm), suitable for lighter structures.
The S355ML S355NL application difference highlights S355NL's versatility for thicker plates and S355ML's cost-effectiveness for thinner ones.
