EN10025-5 S355K2W Weather Resistant Steel Coil
EN10025-5 S355K2W Weather Resistant Steel Coil - High-Strength Atmospheric Corrosion Resistant Structural Steel
Comprehensive technical datasheet for EN 10025-5 S355K2W weather resistant steel coil, including chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Hot rolling, normalising or thermomechanical rolling, cold forming, welding, cutting, machining
- Phone : +8618037372205
- Email : [email protected]
- WhatsApp: Contact via Whtsapp
- WeChat: +8618037372205
EN10025-5 S355K2W Weather Resistant Steel Coil Introduction
S355K2W is a thermomechanically rolled or normalized fine-grain structural steel with improved atmospheric corrosion resistance, specified in EN 10025-5. It is a high-strength low-alloy (HSLA) weathering steel offering a minimum yield strength of 355 MPa and guaranteed impact toughness of 40 J at -20 °C (grade K2). The enhanced weather resistance is achieved by a precisely controlled addition of copper, chromium, nickel, and phosphorus, forming a dense, self-protecting oxide layer that drastically reduces corrosion rates in unpainted outdoor exposure.
- Excellent weldability and cold formability comparable to conventional S355 structural steels.
- Suitable for load-bearing structures, bridges, building façades, containers, and architectural applications exposed to the atmosphere.
- Available as hot-rolled coil, cut-to-length sheet, plate, and wide strip in various thicknesses.
EN10025-5 S355K2W Weather Resistant Steel Coil Chemical Composition
The alloy design of S355K2W targets an atmospheric corrosion resistance index I ≥ 6.0 according to ASTM G101 or EN ISO 9223. The combination of Cu, Cr, Ni, and carefully controlled phosphorus and sulphur promotes the formation of a stable patina. Fine-grain practice is ensured by sufficient aluminium and/or microalloying elements (Nb, V, Ti). All values are based on the ladle analysis as per EN 10025-5:2019.
| Chemical Element | Standard Value (mass %) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.16 | Maximum |
| Silicon (Si) | ≤ 0.50 | Maximum |
| Manganese (Mn) | 0.50 – 1.50 | Range |
| Phosphorus (P) | ≤ 0.030 | Maximum; contributes to atmospheric corrosion resistance |
| Sulphur (S) | ≤ 0.025 | Maximum |
| Chromium (Cr) | 0.40 – 0.80 | Essential for enhanced weathering properties |
| Nickel (Ni) | ≤ 0.65 | Improves toughness and corrosion resistance |
| Copper (Cu) | 0.25 – 0.55 | Key element for stable patina formation |
| Nitrogen (N) | ≤ 0.012 | Maximum; for aluminium-killed fine-grain steel |
| Aluminium (Altotal) | ≥ 0.020 | Minimum for fine-grain treatment |
| Niobium (Nb) | 0.015 – 0.060 | Optional microalloy; grain refinement |
| Vanadium (V) | 0.02 – 0.12 | Optional microalloy; grain refinement |
| Titanium (Ti) | 0.02 – 0.10 | Optional microalloy; grain refinement |
| Molybdenum (Mo) | ≤ 0.30 | Permitted residual; may improve strength |
| Zirconium (Zr) | ≤ 0.15 | Permitted residual |
EN10025-5 S355K2W Weather Resistant Steel Coil Thermal and Electrical Physical Properties
Physical properties are indicative for S355K2W weathering steel at room temperature unless otherwise stated. These values are derived from typical unalloyed/low-alloyed structural steels and may show minor variations depending on exact chemical composition and heat treatment condition. They are suitable for engineering calculations and FEM simulations.
| Property | Typical Value | Unit | Test Condition / Reference Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of elasticity (E) | 210 | GPa | At 20 °C, static modulus |
| Shear modulus (G) | 81 | GPa | At 20 °C, calculated |
| Poisson's ratio (ν) | 0.3 | – | Elastic range |
| Coefficient of thermal expansion (α) | 11.7 | ×10⁻⁶ K⁻¹ | Between 20 °C and 100 °C |
| Thermal conductivity (λ) | 45 | W/(m·K) | At 20 °C |
| Specific heat capacity (cp) | 460 | J/(kg·K) | At 20 °C |
| Electrical resistivity (ρe) | ~0.20 | ×10⁻⁶ Ω·m | At 20 °C, typical for weathering steel |
EN10025-5 S355K2W Weather Resistant Steel Coil Mechanical Properties
Mechanical properties are guaranteed in the delivery condition for flat and long products. Values depend on the nominal thickness. S355K2W meets the requirements for the K2 quality class: KV2 ≥ 40 J at -20 °C (longitudinal). Test pieces are taken in accordance with EN 10025-1 and EN ISO 6892-1 (tensile) and EN ISO 148-1 (impact). Bending test is performed as per EN ISO 7438.
| Property | Standard Requirement / Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Yield strength (ReH) | ≥ 355 | MPa | Nominal thickness ≤ 16 mm, transverse |
| Yield strength (ReH) | ≥ 345 | MPa | Nominal thickness 16 < t ≤ 40 mm |
| Yield strength (ReH) | ≥ 335 | MPa | Nominal thickness 40 < t ≤ 63 mm |
| Yield strength (ReH) | ≥ 325 | MPa | Nominal thickness 63 < t ≤ 80 mm |
| Yield strength (ReH) | ≥ 315 | MPa | Nominal thickness 80 < t ≤ 100 mm |
| Tensile strength (Rm) | 470 – 630 | MPa | All thicknesses ≤ 100 mm |
| Elongation (A) | ≥ 22 | % | Nominal thickness ≤ 40 mm, longitudinal, proportional test piece |
| Elongation (A) | ≥ 21 | % | Nominal thickness 40 < t ≤ 63 mm |
| Elongation (A) | ≥ 20 | % | Nominal thickness 63 < t ≤ 80 mm |
| Elongation (A) | ≥ 20 | % | Nominal thickness 80 < t ≤ 100 mm |
| Impact energy (KV2) | ≥ 40 | J | At -20 °C, longitudinal, Charpy V-notch; K2 requirement |
| Bend test (180°) | No cracks | – | Bend mandrel diameter: 2t for t ≤ 16 mm; 3t for 16 < t ≤ 40 mm; transverse or longitudinal |
EN10025-5 S355K2W Weather Resistant Steel Coil Fully Equivalent Material Standards and Alternative Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5 | S355K2W | Original grade; K2 impact quality (-20 °C/40 J) with improved atmospheric corrosion resistance |
| United States | ASTM A588/A588M | Grade K (or Grade H, C) – typically A588 Gr. K | Yield strength approx. 345 MPa (50 ksi); similar Cr-Cu-Ni chemistry. Impact testing upon agreement. |
| United States | ASTM A709/A709M | Grade 50W (or HPS 50W) | Structural steel for bridges; comparable strength and weathering characteristics. |
| Japan | JIS G3114 | SMA490CW (also SMA490BW) | Weathering steel with minimum yield 365 MPa, tensile 490–610 MPa; C-class -20 °C impact. Direct substitution possible. |
| China | GB/T 4171 | Q355NHE (or Q355NH with fine-grain treatment) | Weather-resistant structural steel with YS ≥355 MPa; impact quality adapted per suffix. NHE: normalised or TM, fine grain. |
| International | ISO 4952 (similar concept) | Fe355W-K2W (approximate designation) | Not an official ISO grade; often referred to as equivalent to S355K2W when combining ISO Fe355W with toughness code. |
EN10025-5 S355K2W Weather Resistant Steel Coil Application Introduction
S355K2W is designed for welded, bolted, and riveted structures where durability in atmospheric exposure is critical. Its self-protecting patina eliminates the need for painting in many rural, urban, and light industrial environments, reducing life-cycle costs. With its guaranteed low-temperature toughness, it is especially suitable for bridges and heavy constructions in cold climates.
Product Applications: Hot-rolled coils and cut-to-length sheets for fabrication, Plates for heavy welded structures, Welded H-beams and box sections, Corten-equivalent architectural panels, Pre-fabricated bridge girders and railway wagon components, Weather resistant tube and hollow sections (through further processing)
Processed into products: Bridge main girders, cross-beams, and stiffeners, Architectural façades and rain screens, Ship container walls and frames, Overhead sign supports and lighting poles, Rail wagon body panels and underframes, Wind turbine tower shell plates, Agricultural and industrial building frames
Application industries: Civil and structural engineering (bridges, highway gantries, noise barriers), Building construction (façades, roofing, exposed architectural frameworks), Railway vehicle manufacturing (wagons, freight cars, containers), Ship and offshore (weather decks, non-critical structural components), Energy (transmission towers, wind turbine towers, solar support structures), Industrial equipment (fans, silos, cladding, chimneys)
EN10025-5 S355K2W Weather Resistant Steel Coil Closely Related Alternative Materials for Consideration
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5 | S355J2W | Same strength and chemical range but reduced impact energy (≥27 J at -20 °C). Suitable if K2 toughness is not required. |
| Europe | EN 10025-5 | S355J0W | Impact at 0 °C (min 27 J). Can be acceptable for less demanding temperature conditions. |
| Europe | EN 10025-5 | S355K2WP | Slightly different chemistry with higher phosphorus (0.06-0.15%) for enhanced patina in urban environments. Equivalent strength. |
| United States | ASTM A588/A588M | Grade A, Grade B | Yield strength 345 MPa; general-purpose weathering steel. Chemistry differs from K2W; verify impact requirements. |
| United States | ASTM A606 / A606M | Type 4 | High-strength, low-alloy, improved atmospheric corrosion resistance for sheet and strip. Suitable for thinner gauges. |
| UK / Former BS | BS 4360 (obsolete) | WR 50 C (or 50D) | Historical weathering steel equivalent with yield 355 MPa; replaced by EN 10025-5. |
Notes:
Important: All data presented here are based on the official EN 10025-5 standard and typical reference values. Actual properties may vary depending on mill practice, thickness, and processing route. For critical applications, the user should verify with the mill certificate (EN 10204 type 3.1). Welding consumables must match the weathering characteristics to maintain uniform corrosion resistance. When exposed to chlorides (coastal/marine), periodic washing or supplementary coating may be necessary to prevent excessive corrosion.
- Share
