355J2WP Weathering Steel Core Standards Explained

EN 10025-5 covers hot-rolled structural steel products in weathering grades. It specifies chemical composition, mechanical properties, and delivery conditions. S355J2WP is one of several grades within this standard, sitting alongside S355J0WP, S355K2G1W, S355K2G2W, and others.

Key chemical limits (EN 10025-5 for S355J2WP):

Element    Requirement (by % mass, max unless noted)
Carbon (C)    ≤0.16%
Silicon (Si)    0.15–0.50%
Manganese (Mn)    0.50–1.50%
Phosphorus (P)    ≤0.035% (base) — elevated specified for corrosion
Sulfur (S)    ≤0.030%
Copper (Cu)    0.25–0.55%
Chromium (Cr)    0.40–0.80%
Nickel (Ni)    ≤0.65%
Note: Specific limits for "P" variants may allow elevated phosphorus per the standard's corrosion-resistant design. Always verify the specific order requirement.

Mechanical properties per EN 10025-5:

Yield strength (ReH): ≥355 MPa for thickness ≤16mm (steps down with increasing thickness per standard table)

Tensile strength (Rm): 470–630 MPa (thickness-dependent range)

Elongation (A): ≥20% (typical, specimen-dependent)

Impact toughness (J2): ≥27J at -20°C (Charpy V-notch)

Testing and compliance.

EN 10025-5 requires that each plate or section be tested from the same heat. The mill certificate must include:

Chemical analysis (heat analysis and, for certain elements, product analysis)

Tensile test results (yield, tensile, elongation)

Impact test results (temperature and energy absorbed)

Plate dimensions and heat number

All tests follow EN ISO 6892-1 for tensile and EN ISO 148-1 for Charpy impact.

Delivery conditions.

S355J2WP is typically delivered as-rolled, normalised-rolled, or thermomechanically rolled (depending on thickness and mill practice). The standard allows the manufacturer to choose the rolling process as long as properties meet requirements.

Deoxidation. The standard requires fully killed steel for S355J2WP (aluminum or silicon-aluminum killed). This ensures consistent internal quality and good weldability.

What the standard doesn't tell you.

EN 10025-5 provides the framework—but it doesn't design your joint, specify your weld procedure, or tell you where to add weep holes. Those are engineering decisions. The standard only guarantees that the material itself meets minimum requirements.

Three things to verify on your mill certificate.

Grade designation: Confirm it says S355J2WP—not S355J0WP (0°C impact) or S355K2G1W (different chemistry/impact rule).

Impact temperature: -20°C clearly stated on the test report.

Thickness-dependent values: Yield and tensile requirements change with thickness—make sure the reported values align with your actual plate thickness.

A practical standard-compliance checklist.

When you order S355J2WP under EN 10025-5, ensure your purchase order includes:

The grade (S355J2WP)

Product form (plate, sheet, or section)

Dimensions (thickness, width, length)

Delivery condition (as-rolled or other)

Testing requirements (standard or supplementary)

Any special impact testing or nondestructive examination beyond standard