EN 10025-2 S355K2 Steel for ERW Pipe
EN 10025-2 S355K2 Steel for ERW Pipe: High-Strength, Low-Temperature Toughness
Comprehensive technical data on S355K2 steel to EN 10025-2, optimized for ERW pipe production. Chemical composition, mechanical properties, thermal & electrical performance, international equivalents, and typical applications.
Hot rolling, normalizing, thermomechanical rolling, cold forming, welding (ERW, SAW, etc.)
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EN 10025-2 S355K2 Steel for ERW Pipe Introduction
S355K2 is a hot-rolled structural steel grade specified in EN 10025-2:2019, designed for welded structures such as electric resistance welded (ERW) pipes. It belongs to the fine-grain, low-alloy high-strength steels with a minimum yield strength of 355 MPa for thicknesses up to 16 mm. The "K2" designation guarantees a minimum impact energy of 40 J at -20 °C (longitudinal), making it suitable for demanding low-temperature applications.
- Excellent weldability with appropriate procedures
- Good ductility and formability for cold forming and ERW tube manufacturing
- Fine-grained microstructure ensures reliable toughness
- Delivered in normalized or thermomechanical rolled condition, often as strip or plate for tubular products
EN 10025-2 S355K2 Steel for ERW Pipe Chemical Composition
Chemical requirements according to EN 10025-2:2019 for S355K2. Values are ladle analysis, applicable for product thickness ≤ 100 mm unless otherwise agreed. Elements like Nb, V, Ti are used for grain refinement. Note: Cu content may be specified when weather resistance is required.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.20 | Thickness ≤ 16 mm; for >16 mm ≤ 0.22 |
| Silicon (Si) | ≤ 0.50 | |
| Manganese (Mn) | 0.90 – 1.65 | For thickness ≤ 40 mm; >40 mm may be 0.90 – 1.70 |
| Phosphorus (P) | ≤ 0.030 | |
| Sulfur (S) | ≤ 0.025 | |
| Nitrogen (N) | ≤ 0.012 | For Al-killed or nitrogen binding elements |
| Aluminium (Al total) | ≥ 0.020 | If used for grain refinement; or other nitrogen binding elements |
| Chromium (Cr) | ≤ 0.30 | Optional element |
| Nickel (Ni) | ≤ 0.30 | |
| Molybdenum (Mo) | ≤ 0.10 | |
| Copper (Cu) | ≤ 0.55 | May be specified for certain applications |
| Titanium (Ti) | ≤ 0.05 | Grain refinement element |
| Vanadium (V) | ≤ 0.12 | Grain refinement element |
| Niobium (Nb) | ≤ 0.05 | Grain refinement element |
EN 10025-2 S355K2 Steel for ERW Pipe Thermal and Electrical Physical Properties
Typical physical properties for S355K2 steel at ambient temperature. These values are indicative for design calculations and may vary slightly with actual composition and microstructure. Data are based on standard low-alloy structural steels.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | Room temperature |
| Modulus of Elasticity (E) | 210 | GPa | Room temperature |
| Shear Modulus (G) | 81 | GPa | Room temperature |
| Poisson's Ratio (ν) | 0.3 | — | Elastic range |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 20–100 °C |
| Thermal Expansion Coefficient (α) | 13.0 | 10⁻⁶/K | 20–200 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | At 20 °C |
| Thermal Conductivity (λ) | 47 | W/(m·K) | At 200 °C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | At 20 °C |
| Specific Heat Capacity (cp) | 500 | J/(kg·K) | At 200 °C |
| Electrical Resistivity (ρe) | 0.15 | μΩ·m | At 20 °C |
EN 10025-2 S355K2 Steel for ERW Pipe Mechanical Properties
Mechanical properties at room temperature per EN 10025-2:2019 for S355K2. Values vary with nominal thickness. Impact energy refers to Charpy V-notch test on longitudinal specimens. For ERW pipe, the base material (strip/plate) properties apply unless regulated by pipe standard (e.g., EN 10219-1).
| Property | Standard Value | Unit | Test Condition / Thickness Range |
|---|---|---|---|
| Yield Strength (ReH) | 355 | MPa | t ≤ 16 mm |
| Yield Strength (ReH) | 345 | MPa | 16 mm < t ≤ 40 mm |
| Yield Strength (ReH) | 335 | MPa | 40 mm < t ≤ 63 mm |
| Yield Strength (ReH) | 325 | MPa | 63 mm < t ≤ 80 mm |
| Yield Strength (ReH) | 315 | MPa | 80 mm < t ≤ 100 mm |
| Yield Strength (ReH) | 295 | MPa | 100 mm < t ≤ 150 mm |
| Yield Strength (ReH) | 285 | MPa | 150 mm < t ≤ 200 mm |
| Yield Strength (ReH) | 275 | MPa | 200 mm < t ≤ 250 mm |
| Tensile Strength (Rm) | 470 – 630 | MPa | All thicknesses |
| Elongation after fracture (A) | ≥ 22 | % | Longitudinal, t ≤ 16 mm, gauge L0=5.65√S0 |
| Elongation after fracture (A) | ≥ 22 | % | 16 mm < t ≤ 40 mm |
| Elongation after fracture (A) | ≥ 21 | % | 40 mm < t ≤ 63 mm |
| Elongation after fracture (A) | ≥ 20 | % | 63 mm < t ≤ 80 mm |
| Elongation after fracture (A) | ≥ 20 | % | 80 mm < t ≤ 100 mm |
| Elongation after fracture (A) | ≥ 18 | % | 100 mm < t ≤ 150 mm |
| Elongation after fracture (A) | ≥ 17 | % | 150 mm < t ≤ 200 mm |
| Elongation after fracture (A) | ≥ 17 | % | 200 mm < t ≤ 250 mm |
| Impact Energy (KV, longitudinal) | ≥ 40 | J | At -20 °C |
| Impact Energy (KV, transverse) | ≥ 27 | J | At -20 °C (if agreed) |
EN 10025-2 S355K2 Steel for ERW Pipe Completely Equivalent Material Standards & Alternative Designations
| Country / Region | Standard / Specification | Grade / Designation | Remarks |
|---|---|---|---|
| Europe | EN 10025-2:2019 | S355K2 | Base standard, same chemical and mechanical requirements |
| Germany | DIN EN 10025-2 | S355K2 | Identical adoption |
| United Kingdom | BS EN 10025-2 | S355K2 | Identical adoption |
| France | NF EN 10025-2 | S355K2 | Identical adoption |
| Italy | UNI EN 10025-2 | S355K2 | Identical adoption |
| Spain | UNE EN 10025-2 | S355K2 | Identical adoption |
| Sweden | SS 14 | 2134-01 | Similar, but check impact temperature; SS 2134-01 covers S355K2 |
| International | ISO 630-2:2011 | S355K2 | Identical technical requirements |
| International (Hollow Sections) | EN 10219-1:2006 | S355K2H | Cold-formed welded structural hollow sections; same base steel but with slightly adjusted mechanicals for profile forming |
EN 10025-2 S355K2 Steel for ERW Pipe Application Introduction
S355K2 ERW pipes are employed where a combination of high strength, good weldability, and reliable low-temperature toughness is required. The fine-grained structure ensures ductile behavior even in cold climates. Typical uses span structural engineering, mechanical equipment, and energy transmission.
Product Applications: Electric resistance welded (ERW) pipes and tubes, Structural hollow sections (circular, square, rectangular), Spiral-welded pipes for water transmission, Scaffolding tubes and accessories, Piling pipes and tubular foundations, Conveyor rollers and idlers, Mechanical tubing for hydraulic cylinders, Poles for lighting, transmission, and telecom
Processed into products: Columns, beams, and trusses, Bridge bracing and chords, Offshore platform legs and braces, Wind turbine tower sections and internal platforms, Pipeline risers and onshore flowlines, Truck chassis rails and crane booms, Scaffold standards, ledgers, and couplers, Formwork struts and falsework, Agricultural equipment frames and toolbars
Application industries: Building and construction, Civil engineering (bridges, stadiums, airports), Offshore and marine structures, Wind energy and tower fabrication, Oil and gas pipelines (sweet service), Mining and earth-moving equipment, Automotive chassis and trailer manufacturing, Agricultural machinery, Process plant and pipework
EN 10025-2 S355K2 Steel for ERW Pipe Similar / Alternative Material Recommendations
| Country / Region | Standard / Specification | Grade / Designation | Remarks |
|---|---|---|---|
| USA | ASTM A572/A572M | Grade 50 [345] (Type 1) | Yield strength 345 MPa (50 ksi), impact requirements differ; Charpy V-notch 27 J at temperature by specification (e.g., A709/A913) |
| Japan | JIS G 3106 | SM490B (or SM490YB) | Yield 325–365 MPa, Charpy 27 J at 0°C (SM490B), need to verify -20°C toughness |
| China | GB/T 1591-2018 | Q355D | Yield 355 MPa, Charpy 27 J at -20°C; very close but manganese range slightly different |
| India | IS 2062:2011 | E350BR | Minimum yield 350 MPa, impact at -20°C (longitudinal 27 J); closely comparable |
| Russia | GOST 27772-88 | C345-4 (S345-4) | Yield 345 MPa, impact -20°C ≥ 34 J; check for seamless/welded pipe equivalent |
Notes:
- S355K2 is weldable by all common processes (ERW, SAW, GMAW, SMAW). Preheat and interpass temperature should be controlled according to thickness and hydrogen control requirements.
- For ERW pipe, the heat-affected zone of the weld seam may exhibit local softening; design considerations should account for this if high deformation is expected.
- When ordering ERW pipe to EN 10219-1, the designation becomes S355K2H; the tensile properties values are slightly adjusted (yield is 355 MPa for t≤16 mm, but elongation can differ).
- Alternative impact temperatures: K2 guarantees 40 J at -20°C (longitudinal). If lower temperature toughness is needed, refer to grades like S355J2 (27 J at -20°C) or S355NL (fine grain, lower temperature).
- For elevated temperature design, the properties reduce; consult EN 1993-1-2 for structural fire engineering.
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