EN 10025-2 S355J0 is a high-strength low-alloy (HSLA)  structural steel grade widely used in construction and engineering due to its good strength, weldability, and toughness. It is part of the S355 series, with the "J0" suffix indicating impact testing at 0°C (instead of -20°C or -30°C for other variants like S355J2 or S355K2).

Standard and Grade Designation

Standard: EN 10025-2

This is the European standard for "Hot rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steels."

Grade: S355J0

"S" = Structural steel

"355" = Minimum yield strength of 355 MPa (at ≤16mm thickness)

"J0" = Impact toughness requirement at 0°C (27J min, longitudinal Charpy V-notch test)

Material Type: Non-alloy steel (but may contain small amounts of alloying elements like Mn, Si, etc.)

Delivery Condition: Typically hot-rolled (as-rolled) or normalized

Key Features:

✔ High strength-to-weight ratio

✔ Good weldability and formability

✔ Cost-effective for structural applications

✔ Reliable impact resistance at low temperatures (0°C)

Note: The actual yield strength value decreases as the material thickness increases.

1. Building & Bridge Construction (beams, columns, frames)

2. Heavy Machinery & Equipment (cranes, forklifts, trailers)

3. General Fabrication (brackets, supports, platforms)

4. Shipbuilding & Offshore Structures (non-critical parts)

Fabrication & Processing:

Cutting: Suitable for laser, plasma, flame, or shear cutting.

Welding: Compatible with SMAW, GMAW, FCAW, SAW (preheat if thickness >25mm).

Forming: Can be cold-formed; annealing may help for severe bends.

Heat treatment: Typically supplied in the "hot-rolled condition" (no additional heat treatment required). If increased hardness is needed, normalizing treatment (heating to 850-950°C followed by air cooling) can be performed, though this may slightly reduce toughness.

Precautions for Procurement and Inspection

Delivery Condition: Default is "as-rolled (AR)." If normalized (N) or controlled rolled (CR) condition is required, it must be specified in the order (controlled rolled steel generally offers better toughness).

Quality Certificate: Suppliers must provide a quality certificate compliant with EN 10204 standards, including:

1. Certificate: Includes test results for chemical composition and mechanical properties, suitable for most structural engineering applications.

2. Certificate: Requires third-party inspection agency involvement (e.g., SGS, BV) for witness testing, applicable to high-demand scenarios (e.g., bridges, pressure vessels).

Thickness Tolerance: The thickness tolerance grade (e.g., "normal tolerance" or "high precision tolerance" as per EN 10025-2) must be selected based on the application to avoid affecting structural load calculations.

Surface Quality: Default is "usual surface (U)." For applications with high aesthetic requirements (e.g., exposed steel structures), specify "improved surface (R)" to minimize surface defects (e.g., scratches, scale).



Comparison with Other Grades:

Comparison with Other S355 Grades:

Summary

EN 10025-2 S355J0 is a high-strength structural steel plate with excellent toughness at ambient temperatures and good processability. It is widely used in industrial and construction applications globally. Key factors to consider during procurement include yield strength, impact toughness, and the compliance of quality certificates.