What Is S355J2WP Steel Plate?
S355J2WP is a hot-rolled structural steel with anti-corrosion properties, also called weathering steel or atmospheric corrosion-resistant steel, supplied under EN 10025-5. The designation S355 means a minimum yield strength of 355 MPa, J2 requires impact energy of at least 27 J at −20 °C, and WP identifies the phosphorus-alloyed weathering variant.
The grade is produced as sheet, coil, beam, bar, flat bar and channel, which makes it suitable for a wide range of structural engineering uses where long-term exposure to the atmosphere is expected.
Chemical Composition
Table 1 lists the product analysis limits for S355J2WP as commonly quoted. The phosphorus content is deliberately held in a range rather than at a maximum value because it contributes to atmospheric corrosion resistance.
| Element (max, %) | S355J2WP |
|---|---|
| Carbon (C) | 0.15 |
| Silicon (Si) | 0.80 |
| Manganese (Mn) | 1.1 |
| Phosphorus (P) | 0.05 – 0.16 |
| Sulfur (S) | 0.035 |
| Chromium (Cr) | 0.25 – 1.35 |
| Copper (Cu) | 0.20 – 0.60 |
The exact limiting values depend on the governing edition of EN 10025-5 and on whether the analysis is a cast (ladle) analysis or a product analysis; the mill test certificate states the values for each delivery.
Mechanical Properties
The guaranteed mechanical values for common thickness ranges are shown below.
| Thickness (mm) | Min. yield strength (MPa) | Tensile strength (MPa) |
|---|---|---|
| ≤ 16 | 355 | 470 – 630 (3 mm < t ≤ 100 mm) |
| 16 – 40 | 345 | 470 – 630 |
| sheet ≤ 3 | - | 510 – 680 |
For thin sheet, elongation is specified on gauge length L₀ = 80 mm, with minimum values of 14–16% depending on thickness, rising to 20% for sheet over 3 mm. Full thickness-dependent values should be taken from the standard or the certificate.
Available Forms, Dimensions and Delivery States
Thickness: cold-rolled sheet 0.5–2 mm; hot-rolled plate 2–300 mm (2–100 mm commonly used)
Width: 1000–3000 mm (1000–2200 mm commonly used)
Length: 1000–12000 mm or as required
Surface: clean, finishing, blasting or painting according to customer requirement
Delivery states: hot-rolled, controlled rolling, normalising, annealing, tempering, quenching, N+T and Q+T
Quality: a mill test certificate (MTC) is provided with the goods; third-party inspection such as BV or SGS can be arranged
Typical Applications
Metal constructions: buildings, bridges and ships
Transmission towers and reaction towers
Lifting and transport machinery
Industrial furnaces and boilers
Container frames, warehouse goods shelves and similar exposed structures
Frequently Asked Questions
What does the WP in S355J2WP mean?
WP identifies the phosphorus-alloyed weathering grade. The controlled, elevated phosphorus range improves atmospheric corrosion resistance compared with the standard W grades.
Which standard applies to S355J2WP?
EN 10025-5, the European standard for structural steels with improved atmospheric corrosion resistance; the edition in force at the time of order applies.
What thicknesses are available?
Cold-rolled sheet from 0.5 mm to 2 mm and hot-rolled plate from 2 mm to 300 mm are commonly supplied, with 2–100 mm being the usual working range for plate.
What delivery states can be ordered?
Hot-rolled, controlled rolling, normalising, annealing, tempering, quenching, N+T and Q+T are all possible; the required state and the +AR/+N/+M symbols should be stated in the order.
Is S355J2WP weldable?
Yes. It is a structural weathering steel with good weldability; welding consumables and procedures should be selected so that the weld zone provides corrosion behaviour matching the parent material.
How does S355J2WP differ from S355J2W?
Both are 355 MPa weathering steels with J2 (27 J at −20 °C) impact performance. The WP variant uses a controlled phosphorus range to enhance atmospheric corrosion resistance, while the W variant relies mainly on chromium and copper additions.
