Project Description
E355K2 (1.0920) is an alloy quality steel seamless circular tube specified under EN 10297-1 for mechanical and general engineering applications. The designation “E” identifies an engineering steel, “355” denotes the minimum yield strength of 355 MPa in the normalized (+N) delivery condition, and the suffix “K2” guarantees impact toughness of ≥40 J at −20 °C (longitudinal) — making it the highest-impact-toughness variant in the 355 MPa class under the EN 10297-1 framework. The K2 designation mandates a fully killed, fine-grain-practised steel with Al ≥0.020% and controlled nitrogen (N ≤0.015%), ensuring resistance to brittle fracture in cold-climate and dynamically loaded service. Supplied by FUSHUN METAL under ISO 9001 and AS9120B certified quality management, every heat is delivered with EN 10204 Type 3.1 traceability including mandatory Charpy V-notch test reports. E355K2 seamless tubes are widely specified for cold-climate machinery, lifting and hoisting equipment, agricultural implements, railway rolling stock, wind energy structures, and welded fabrications where assured notch toughness at sub-zero temperatures is a mandatory design requirement.
E355K2 — Equivalent Grades
| Standard | Grade | Remarks |
|---|---|---|
| EN 10025-2 | S355K2 | Hot-rolled structural; −20 °C Charpy; closest EN grade |
| DIN 17100 | St 52-3 | 355 MPa class; no K2 impact guarantee |
| ASTM A572 | Gr 50 [345] | 345 MPa yield; no impact class; verify toughness |
| JIS G3106 | SM490YA | 365 MPa yield; Charpy at 0 °C; match K2 requirement |
| BS 4360 | 50D | 355 MPa yield; −20 °C impact; British equivalent |
| JIS G3445 | STKM 16A | Mechanical tubing; 490 MPa tensile min.; no Charpy |
Typical Applications of E355K2 Seamless Tubes
Arctic-grade excavator booms, bulldozer push arms, snow groomer frames, and forestry harvester heads. The K2 impact guarantee at −20 °C eliminates brittle fracture risk during cold-start operation and sustained low-temperature service in northern-latitude and high-altitude environments.
Mobile crane lattice booms, tower crane mast sections, overhead crane bridge girders, and forklift mast channels. Certified K2 Charpy values ensure structural integrity under dynamic and impact loading at the minimum design temperature.
Plough frames, harrow beams, tillage tool bars, subsoiler shanks, and combine harvester chassis members. E355K2 absorbs shock and vibration loads at operating temperatures down to −20 °C without ductile-to-brittle transition failure.
Bogie bolster beams, wagon underframe members, draw-gear components, and container spreader bars. −20 °C Charpy compliance is a standard procurement requirement in UIC and EN 12663 rolling-stock design codes, which E355K2 satisfies without supplementary testing.
Wind turbine tower internals, nacelle frames, access platforms, and solar tracker torque tubes. K2-grade Charpy values are routinely required in turbine certification standards (IEC 61400) for structures exposed to cold climate operation.
Bracing members, columns, truss chords, and bolted connections in outdoor steel structures. The killed, fine-grain Al-treated chemistry provides uniform properties in all directions and excellent weldability for site fabrication in cold regions.
E355K2 Supply Dimensions
FUSHUN METAL supplies EN 10297-1 E355K2 seamless tubes across three manufacturing routes. Standard delivery condition is normalized (+N). Incoming dimensional verification, OES chemistry checks, and Charpy V-notch testing at −20 °C are performed on every heat lot sourced from ISO 9001 and AS9120B-certified production lines before release.
| OD | 26.9 – 660.0 mm |
| WT | 2.6 – 75.0 mm |
| Length | 5.0 – 14.0 m |
| OD | 6.0 – 220.0 mm |
| WT | 0.5 – 30.0 mm |
| Length | 4.0 – 12.5 m |
| OD | 10.0 – 120.0 mm |
| WT | 0.8 – 12.0 mm |
| Length | 4.0 – 12.0 m |
Custom cut-to-length, bevel end preparation, and honed/SRB internal finishing are available on request. FUSHUN METAL can arrange third-party inspection and witness Charpy testing at independent laboratories per customer specifications.
E355K2 Chemical Composition (Ladle Analysis, %)
| C | Si | Mn | P | S | V | Al | Cr | Ni | N |
|---|---|---|---|---|---|---|---|---|---|
| ≤0.20 | ≤0.50 | 0.90–1.65 | ≤0.035 | ≤0.030 | ≤0.12 | ≥0.020 | ≤0.30 | ≤0.50 | ≤0.015 |
Supplemental limits: Mo ≤0.10%, Cu ≤0.35%, Nb ≤0.05%, Ti ≤0.03%. The three defining chemical features of the K2 subgrade are: (1) mandatory Al ≥0.020% for full killing and fine-grain practice; (2) N ≤0.015% to suppress strain ageing and preserve notch toughness after cold forming; (3) Mn 0.90–1.65% with a lower limit guaranteeing pearlite volume fraction sufficient for grain refinement during normalizing. Vanadium (V ≤0.12%) can be added optionally; when used, the combined Nb+V content is restricted to ≤0.20% to avoid elevating the ductile-to-brittle transition temperature. FUSHUN METAL verifies chemistry via OES on every incoming heat and retains spectral records for the full traceability chain.
E355K2 Mechanical Properties — Normalized (+N)
| Wall Thickness (mm) | YS ReH (MPa) | TS Rm (MPa) | Elong. A (%) | KV2 −20 °C (J) | Hardness HBW |
|---|---|---|---|---|---|
| ≤16 | ≥355 | ≥490 | ≥20–22 | ≥40 (L) / ≥27 (T) | 140–190 |
| 16–40 | ≥345 | ≥490 | ≥20–22 | ≥40 (L) / ≥27 (T) | 135–185 |
| 40–65 | ≥335 | ≥470 | ≥20–22 | ≥40 (L) / ≥27 (T) | 130–180 |
| 65–80 | ≥315 | ≥470 | ≥18–20 | ≥40 (L) / ≥27 (T) | 125–175 |
| 80–100 | ≥295 | ≥470 | ≥18–20 | ≥40 (L) / ≥27 (T) | 120–170 |
The defining capability of E355K2 is its dual guarantee of 355 MPa minimum yield strength and −20 °C Charpy V-notch impact toughness of ≥40 J — the most stringent impact requirement among EN 10297-1 engineering tube grades at this strength level. Normalizing is performed at 890–930 °C followed by still-air cooling, producing a uniform ferrite-pearlite microstructure with AlN and optional V(C,N) precipitates pinning prior-austenite grain boundaries. The five-tier yield strength curve reflects the intrinsic through-thickness cooling-rate dependency of normalized C-Mn steel. Compared with standard E355 (which has no Charpy requirement and no minimum Al or Mn), the K2 subgrade adds substantial fracture-safety margin for dynamically loaded, cold-climate service. FUSHUN METAL issues EN 10204 Type 3.1 certification with full tensile and Charpy results for every shipment.
E355K2 — Additional Product Data
Standard delivery: normalized (+N) at 890–930 °C, still-air cooled. Seamless process only (hot-finished, cold-drawn, or cold-rolled). Fully killed, fine-grain-practised steel with Al ≥0.020% and ASTM E112 grain size 6 or finer. FUSHUN METAL sources exclusively from ISO 9001 and AS9120B-certified mills with full process audit traceability and normalizing cycle records.
Mandatory: ladle analysis, room-temperature tensile test, Charpy V-notch at −20 °C (longitudinal, one set per heat treatment batch), flattening test, dimensional and visual inspection, EN 10204 Type 3.1. Optional: product analysis, transverse Charpy, hardness (Brinell), ultrasonic per EN 10893-10, eddy current per EN 10893-2, through-thickness tensile (Z-quality).
Excellent weldability with all common processes (MIG/MAG, TIG, MMA, SAW). No preheat required for wall thickness ≤25 mm; ≥50 °C for 25–50 mm. CEV ≤0.45% (typical, IIW formula). Post-weld stress relief: 530–580 °C, hold 1 min/mm, controlled cool. Good cold formability: bending, flaring, and swaging operations possible; minimum bending radius ≥2.5t for cold forming. Suitable for hot-dip galvanising (HDG) per EN ISO 1461 without LMAC risk due to controlled Si content (≤0.50%).
Surface options: black (as-normalized), pickled & oiled, shot-blasted & primed. Corrosion protection: zinc-rich epoxy primer, hot-dip galvanising per EN ISO 1461, or FBE coating. Standard packing: hexagonal bundled with steel straps, end caps for thin-wall tubes, weatherproof wrapping for sea freight. Custom labelling and bar-coded bundle tags available for multi-grade shipments.
