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 |
Figures are nominal: thickness tolerance to EN 10029 class A can add 4 % on the thinnest plate. We invoice theoretical weight by default and actual weight on request.
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
Export packing of S355K2 steel plate: loose on bearers, bundles ≤ 10 t. Loading: ≤ 6 m: 40' HC 24–25 t; longer by flat-rack. HS code is assigned by surface and alloy: 7208 (hot-rolled), 7209 (cold-rolled), 7210 (coated), 7225 / 7226 (alloy).
| 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
Documentation for S355K2 steel plate starts with the EN 10204 3.1 mill certificate: heat number, analysis, tensile, Charpy and the condition of supply. Third-party 3.2 certification by Lloyd's, BV, TÜV or SGS is ordered per lot. Ultrasonic examination to EN 10160 and additional low-temperature impact tests are quoted together with the plate.
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
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.