What is the difference between S355ML and S355NL?

S355MLand S355NL are very similar low-temperature structural steels with identical strength, toughness, and chemistry — both deliver 355 MPa yield and ≥27 J impact at –50 °C. The only real difference is the manufacturing process and resulting material behavior.

Here’s a clear, practical comparison:

 

Quick Summary Table

Feature	S355NL (EN 10025-3)	S355ML (EN 10025-4)	Winner for Most Projects
Standard	EN 10025-3	EN 10025-4	—
Delivery Condition	Normalized or normalized rolled	Thermomechanical rolled (TMCP)	S355ML
Manufacturing	Separate heat treatment (880–920°C + air cool)	Controlled rolling + accelerated cooling (no extra heat)	S355ML(cheaper, greener)
Residual Stress	Higher	Very low	S355ML
Flatness	Good	Excellent (<3 mm/m)	S355ML
Weld HAZ Toughness	Good	Superior (finer grain)	S355ML
Distortion in Fab	Higher	20–30% less	S355ML
Z35 Through-Thickness	Good	Outstanding	S355ML
Price (Nov 2025)	Baseline	+$60–100/ton	S355NL cheaper, but S355ML better value
Market Share (Offshore Wind)	20–30%	70–80%	S355ML

Key Takeaway: They are twins — but S355ML is the better twin for 90% of modern projects.

Both meet the same mechanical specs:

• Yield: 355 → 285 MPa (by thickness)
• Tensile: 470–630 MPa
• Elongation: ≥22%
• Impact: ≥27 J at –50 °C
• CEV: ≤0.39 (typical 0.35–0.38)

But S355ML (TMCP) wins because:

• No separate normalizing step → lower cost & energy
• Lower residual stress → less distortion after cutting/welding
• Finer, more uniform microstructure → better HAZ toughness
• Better flatness → easier fit-up in fabrication
• Preferred by DNV, ABS, LR for offshore wind monopiles

 

When to Choose S355NL (Normalized)

Only if:

• Your spec explicitly requires normalized delivery
• You're using very thick plates (>150 mm) in a controlled shop with normalizing furnace
• You need slightly lower price and don’t mind minor distortion

Real-World Usage (2025)

Project Type	Preferred Grade
Offshore Wind Monopiles	S355ML(90%+)
Arctic LNG Modules	S355ML
Standard Bridges	S355NL or S355ML
Heavy Cranes	S355ML
Cold-Region Buildings	Either

 

China Market Price (Nov 2025, FOB Shanghai)

Grade	20–50 mm	100–150 mm	Z35 Add-on
S355NL	$650–720	$680–750	+$15–25
S355ML	$710–780	$740–810	Included

Gangsteel factory-direct: 5–10% below market

 

Need Plates Now?

Gangsteel has both S355ML and S355NL in stock with full certs.

Email: admin@gangsteel.com WhatsApp: +86 135 9887 9167 Website: https://gangsteel.net/

 

We ship to the U.S. in 15–25 days (Houston, LA, NY).

Bottom Line: Use S355ML unless your spec forces S355NL. It’s stronger in practice, easier to fabricate, and dominates modern offshore projects.

Let me know your thickness, quantity, and port — I’ll send a quote in 2 hours.

 

Others relative propery of en 10025-4 S355ML