What is S355K2 steel plate?
S355K2 shares every chemistry limit and every strength value with S355J2; the letter K raises the Charpy V-notch requirement at −20 °C from 27 J to 40 J. That margin matters where cracks could start from cyclic loading or impact — crane structures under EN 13001, rail vehicles, mining and quarry equipment, bucket-wheel and stacker structures — and in Eurocode 3 fracture-toughness selection (EN 1993-1-10), where K2 permits a thicker plate at a given temperature and stress than J2 does. In DIN there was no exact predecessor (ST52-3 N came closest), so K2 arrived with EN 10025 in the 1990s and is still a mill-programme item. Most producers deliver it normalised (+N) because reaching 40 J reliably at −20 °C on thick plate needs the fine grain anyway. For truly cold service (−40 °C, −50 °C) the answer is S355NL or S355ML rather than K2.
Chemical composition
| Element | C | Si | Mn | P | S | Cu |
|---|---|---|---|---|---|---|
| max. % (ladle) | 0.20 (≤ 30 mm) / 0.22 | 0.55 | 1.60 | 0.025 | 0.025 | 0.55 |
Identical to S355J2; fully killed. Mills add Nb/V and keep C ≤ 0.18 to reach 40 J. CEV 0.45–0.49.
Mechanical properties
| Thickness | Yield ReH min (MPa) | Tensile Rm (MPa) | Elongation A min | Impact KV (long.) |
|---|---|---|---|---|
| ≤ 16 mm | 355 | 470–630 | 22 % | 40 J at −20 °C |
| > 16–40 mm | 345 | 470–630 | 22 % | 40 J at −20 °C |
| > 40–63 mm | 335 | 470–630 | 21 % | 40 J at −20 °C |
| > 63–80 mm | 325 | 470–630 | 20 % | 40 J at −20 °C |
| > 80–100 mm | 315 | 470–630 | 20 % | 40 J at −20 °C |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| EN 10025-2 | S355J2 | same steel, 27 J |
| EN 10025-3 | S355N | 40 J at −20 °C long. — closest |
| ASTM | A572 Gr. 50 (CVN 30 ft·lbf at −20 °C) | by supplement |
| JIS G3106 | SM490C | 27 J only |
| GB/T 1591 | Q355E | E = −40 °C, 27 J |
| BS 4360 | 50DD | historic |
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 × 6 000–12 000 | to order 4–8 weeks, +N |
| 80–100 mm | 2 000–2 500 × 6 000 | to order 6–8 weeks, +N, UT |
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
Weld as S355J2+N with one extra discipline: qualify the procedure with HAZ Charpy tests at −20 °C to 40 J, because a careless high-heat-input weld can undo the K2 advantage. Basic low-hydrogen consumables with matching toughness (E50 6 or G46 6 M21), preheat 100 °C above 25 mm, heat input 1.0–2.5 kJ/mm, interpass ≤ 250 °C. Cold bending 2 × t; hot forming followed by normalising only.
Where it is used
- Crane structures to EN 13001 and FEM
- Mining, quarry and bulk-handling machines
- Railway vehicles and track equipment
- Cold-region steelwork (Kazakhstan, Balkans highlands, Anatolian plateau)
- Fatigue-loaded welded frames and booms
- Eurocode 3 fracture-toughness upgrades from J2
S355K2 vs S355J2 vs S355NL
J2 → K2 raises impact energy at −20 °C from 27 J to 40 J with the same chemistry — the cheapest toughness upgrade. K2 → NL (EN 10025-3) moves the test temperature to −50 °C with a micro-alloyed fine-grain steel — the upgrade for genuinely cold service and LNG-adjacent structures. Between them sits S355N (40 J at −20 °C, fine grain, normalised) which is technically the nearest match to K2+N. See S355J2 and S355NL.
Price
K2 is an imported mill-programme grade; the band below applies our J2+N premium as reference — final price depends on mill and lot size. Below 20 t we normally quote S355N or S355NL from EU stock as the alternative.
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 S355K2 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. A 40' HC takes 24–25 t of 6 m plate. 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 (one 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 by 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
S355K2 steel plate ships with EN 10204 3.1 certificates cross-referenced to the stencilled heat numbers. Where the project requires it we arrange 3.2 certification with Lloyd's, BV, TÜV or SGS, ultrasonic examination to EN 10160 and Charpy testing at the temperature you specify.
How to order
State thickness × width × length, tonnage, +N, UT and Z requirements, and whether S355N (EN 10025-3) is an acceptable alternative — it often ships sooner.
Standards
- EN 10025-2:2019 — S355K2, 1.0596
- EN 10160 UT on request
- EN 10164 Z-quality on request
- EN 10029 class A/B
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S355K2 · S355J2 · S355NL
Frequently asked questions
What is the difference between S355J2 and S355K2?
Only the impact requirement: 27 J (J) versus 40 J (K) at −20 °C. Chemistry, strength and weldability are identical; K2 is chosen for fatigue- and impact-loaded or cold-region structures.
What does K2 mean in steel grades?
K = 40 J minimum Charpy V-notch energy, 2 = test temperature −20 °C (EN 10027-1 designation system).
Is S355K2 available from stock?
Not in Turkey — it is rolled to order (4–8 weeks); S355N or S355NL from EU stock are the quick alternatives with equal or better toughness.
What is the ASTM equivalent of S355K2?
ASTM A572 Grade 50 with a supplementary Charpy requirement of 30 ft·lbf (≈ 40 J) at −4 °F (−20 °C); A709 Grade 50T3 for bridges is comparable.