What is S355NL steel plate?
EN 10025-3 covers weldable fine-grain structural steels in the normalised or normalised-rolled condition; S355N is the −20 °C grade and S355NL the −50 °C grade. The chemistry is tighter than EN 10025-2: carbon ≤ 0.18 %, sulphur ≤ 0.020 %, and deliberate grain-refining additions of niobium (≤ 0.05 %), vanadium (≤ 0.12 %) and aluminium (≥ 0.020 %). The fine, uniform grain gives high toughness — 27 J at −50 °C transverse-equivalent, and more than 40 J at −20 °C — plus good weldability with a carbon equivalent typically 0.38–0.42. The NL grade is what pressure-vessel and low-temperature codes accept for supporting structures, saddles and skirts around cold service, and what EN 1993-1-10 requires for thick welded members at −30 °C and below. It is a mill-programme plate; Turkish mills roll S355N but the NL version usually comes from EU producers.
Chemical composition
| Element | C | Si | Mn | P | S | Nb | V | Al | Ni | Cr | Mo | N |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| max. % (ladle) | 0.18 | 0.50 | 0.90–1.65 | 0.025 | 0.020 | 0.05 | 0.12 | ≥ 0.020 | 0.50 | 0.30 | 0.10 | 0.015 |
Cu ≤ 0.55, Ti ≤ 0.05. CEV max 0.43 (≤ 63 mm), 0.45 (63–100 mm).
Mechanical properties
| Thickness | Yield ReH min (MPa) | Tensile Rm (MPa) | Elongation A min | Impact KV (long. / trans.) |
|---|---|---|---|---|
| ≤ 16 mm | 355 | 470–630 | 22 % | 27 J at −50 °C (L) / 16 J (T) |
| > 16–40 mm | 345 | 470–630 | 22 % | 27 J at −50 °C |
| > 40–63 mm | 335 | 470–630 | 22 % | 27 J at −50 °C |
| > 63–80 mm | 325 | 470–630 | 21 % | 27 J at −50 °C |
| > 80–100 mm | 315 | 470–630 | 21 % | 27 J at −50 °C |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| EN 10025-3 | S355N | −20 °C version |
| EN 10025-4 | S355ML | thermomechanical −50 °C |
| DIN 17102 | TStE 355 | direct predecessor |
| ASTM | A633 Gr. C/D | normalised HSLA, near |
| ASTM | A537 Cl. 1 | pressure-vessel analogue |
| GB/T 1591 | Q355E (near) | −40 °C |
Thickness range and stock sizes
| Thickness | Widths × lengths | Availability |
|---|---|---|
| 8–20 mm | 2 000 / 2 500 × 6 000–12 000 | to order 4–6 weeks |
| 25–60 mm | 2 000 / 2 500 / 3 000 × 6 000–12 000 | to order 5–8 weeks |
| 80–100 mm | 2 000–2 500 × 6 000 | to order 6–8 weeks, UT standard |
Weight per m² and per plate
| Thickness | kg/m² | 1 500 × 6 000 (kg) | 2 000 × 6 000 (kg) | 2 500 × 12 000 (kg) |
|---|---|---|---|---|
| 8 mm | 62.8 | 565 | 754 | 1 884 |
| 10 mm | 78.5 | 707 | 942 | 2 355 |
| 12 mm | 94.2 | 848 | 1 130 | 2 826 |
| 15 mm | 117.8 | 1 060 | 1 413 | 3 533 |
| 20 mm | 157.0 | 1 413 | 1 884 | 4 710 |
| 25 mm | 196.3 | 1 766 | 2 355 | 5 888 |
| 30 mm | 235.5 | 2 120 | 2 826 | 7 065 |
| 40 mm | 314.0 | 2 826 | 3 768 | 9 420 |
| 50 mm | 392.5 | 3 533 | 4 710 | 11 775 |
| 60 mm | 471.0 | 4 239 | 5 652 | 14 130 |
| 80 mm | 628.0 | 5 652 | 7 536 | 18 840 |
| 100 mm | 785.0 | 7 065 | 9 420 | 23 550 |
Nominal weights — mill tolerance to EN 10029 class A adds up to +4 % on thin plate; invoiced on theoretical weight unless agreed otherwise.
Welding, cutting and forming
Weldable with basic low-hydrogen consumables matched for low-temperature toughness (E46 6 / G46 6 or nickel-alloyed for −50 °C service); preheat 50–100 °C above 25 mm, heat input 1.0–2.5 kJ/mm, interpass ≤ 250 °C, and — this is the difference from ordinary S355 — procedure qualification with Charpy tests at the design temperature on weld metal and HAZ. Cold forming 2 × t; hot forming only with re-normalising; no flame straightening above 650 °C. Order Z25 quality for cruciform joints in thick plate.
Where it is used
- LPG / LNG tank supports, saddles and skirts
- Cold-region steel structures (Kazakhstan, Caucasus, Balkans highlands)
- Wind-turbine towers in cold climates
- Offshore jackets and topside structures
- Railway bridges and dynamic structures at low temperature
- Crane and mining structures to −40 °C
S355NL vs S355J2 vs S355ML
J2 guarantees −20 °C; NL guarantees −50 °C with a normalised fine-grain steel; ML guarantees −50 °C with a thermomechanical steel that has an even lower carbon equivalent (easier welding, no preheat to greater thickness) but cannot be hot-formed. NL is the conservative choice for structures that may be hot-formed or post-weld heat-treated; ML for welded-only fabrication. See S355J2 and S355ML.
Price
S355NL is priced about 200 USD/t over the S235JR base as an imported fine-grain plate; ultrasonic testing, Z-quality and 3.2 inspection are added. The band below is indicative FOB Istanbul.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
We ship S355NL steel plate in strapped skid packs up to 5 t, each plate stencilled with its heat number so the certificate can be matched at the receiving end. Six-metre plate loads 24–25 t into a 40' HC. Plates longer than 6 m or heavier packs are booked on flat-racks or as breakbulk cargo out of Derince. Tariff heading 7208.51 / 7208.52.
| Term | Detail |
|---|---|
| MOQ | 20 t (mill lot) |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | Imported to order 4–8 weeks |
| Packing | Loose on bearers, bundles ≤ 10 t |
| Container / truck | ≤ 6 m: 40' HC 24–25 t; longer flat-rack |
| Documents | Invoice, packing list, EN 10204 3.1 (3.2 on request), certificate of origin; SASO / SONCAP / PVoC on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight for orders above 100 t |
Certificates and testing
Documentation for S355NL steel plate: EN 10204 3.1 mill certificate as standard (heat number, analysis, tensile, Charpy, condition); 3.2 with an independent inspector, EN 10160 UT reports and additional low-temperature Charpy tests are available on plates above 8 mm at order.
How to order
State thickness × width × length, tonnage, design temperature, UT / Z / 3.2 requirements and whether S355ML is acceptable — it is sometimes faster.
Standards
- EN 10025-3:2019 — S355NL, 1.0546
- EN 10160 UT
- EN 10164 Z-quality
- EN 10029 class A/B
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S355NL · S355N · S355ML
Frequently asked questions
What is the difference between S355N and S355NL?
Both are EN 10025-3 normalised fine-grain steels with 355 MPa yield; N is impact-tested at −20 °C (40 J long.) and NL at −50 °C (27 J long.). NL is the low-temperature grade.
Is S355NL the same as S355J2?
No. S355J2 (EN 10025-2) is a conventional structural steel tested at −20 °C; S355NL (EN 10025-3) is a micro-alloyed, normalised fine-grain steel tested at −50 °C with tighter chemistry. NL exceeds J2 in every property.
What is the ASTM equivalent of S355NL?
ASTM A633 Grade C or D (normalised HSLA structural plate) is the nearest; for pressure-vessel supports A537 Class 1 is often accepted.
What is the lead time for S355NL plate?
4–8 weeks — it is imported to order from EU mill programmes; we do not stock it in Turkey.