S355J0 steel plate and the EN 10025-2 framework
S355J0 is a European standard structural steel plate used for welded and bolted load-bearing components. Its technical delivery conditions are set by EN 10025-2, the part of the EN 10025 series that covers non-alloy structural steels, while EN 10025-1 supplies the general delivery requirements that sit above it. The material number of the grade is 1.0553.
The grade is often marketed as an HSLA plate. Strictly speaking S355J0 is a non-alloy quality steel whose 355 MPa minimum yield strength comes from controlled chemistry and rolling practice rather than from deliberate micro-alloying. Where a project genuinely calls for micro-alloyed or fine grain steel, the normalized grades of EN 10025-3 or the thermomechanically rolled grades of EN 10025-4 apply instead, and the two families are not freely interchangeable.
Designation, material number and delivery condition
S – structural steel for constructional use.
355 – minimum yield strength of 355 MPa at room temperature for the thinnest plate.
J – Charpy V-notch impact testing in accordance with EN ISO 148-1.
0 – impact test temperature of 0 °C with a minimum absorbed energy of 27 J.
Material number – 1.0553.
Delivery condition may be hot rolled, normalized or thermomechanically controlled rolled. The condition actually supplied has to be recorded on the inspection document, because toughness, forming behaviour and welding response differ between as-rolled and normalized material even when the grade name is identical.
Chemical composition requirements
| Element | C | Si | Mn | P | S | N | Cu | CEV |
|---|---|---|---|---|---|---|---|---|
| Max % (t ≤ 16 mm) | 0.20 | 0.55 | 1.60 | 0.035 | 0.035 | 0.012 | 0.55 | 0.45 (t ≤ 30 mm) |
Carbon, manganese and the carbon equivalent value control strength and weldability, while phosphorus and sulfur are held low to protect toughness. The limits tighten for the lower-temperature subgrade: S355J2 requires phosphorus and sulfur at 0.025 % maximum, which is one of the practical differences between the J0 and J2 variants. Because limits also vary with product form and thickness, the inspection certificate issued for the supplied heat is the governing record.
Mechanical properties of S355J0 plate
| Nominal thickness (mm) | to 3 | 3–100 | 100–250 |
|---|---|---|---|
| Tensile strength Rm (MPa) | 510–680 | 470–630 | 450–600 |
| Nominal thickness (mm) | ≤16 | >16–40 | >40–63 | >63–80 | >80–100 | >100–150 | >150–200 | >200–250 |
|---|---|---|---|---|---|---|---|---|
| Minimum yield strength ReH (MPa) | 355 | 345 | 335 | 325 | 315 | 295 | 285 | 275 |
| Property | Requirement |
|---|---|
| Minimum elongation A, Lo = 5.65√So (%) | 22 for thickness up to 40 mm, easing for heavier plate |
| Charpy V-notch impact energy, longitudinal | 27 J minimum at 0 °C |
Yield strength falls as thickness increases, so design calculations should use the value that belongs to the gauge actually ordered. The impact requirement is what distinguishes S355J0 from S355JR, which is tested at +20 °C, and from S355J2, which is tested at -20 °C.
Machining, welding and fabrication notes
The grade is suitable for general machining operations. Its high ductility can make chip control and surface finish more difficult than in free-cutting steels, so cutting parameters and tool geometry matter. A higher sulfur content improves machinability and is used in long products intended for machining, but the same sulfur also lowers impact toughness and increases the risk of solidification cracking, which is why free-cutting chemistry should not be applied to welded plate. Calcium treatment is used for inclusion shape control and improves both machinability and through-thickness behaviour.
For welding, low-hydrogen consumables matched to the parent metal strength are the normal choice. Preheating is governed by thickness, carbon equivalent and restraint rather than by the grade name alone, and a qualified welding procedure remains the reference for heavy or highly restrained joints.
Applications and documentation
S355J0 plate is used for bridges, ship structures, power station equipment, lifting and transport machinery, general machinery manufacturing and welded structural components that carry higher loads. Because the grade is selected for its balance of strength, toughness and weldability, it appears wherever a structure must absorb service loads and occasional dynamic events without brittle behaviour.
Supply is normally accompanied by a mill test certificate to EN 10204 3.1 or 3.2, with dimensional tolerances to EN 10029 and marking to EN 10025-1. Additional non-destructive testing such as ultrasonic examination can be specified for critical applications.
FAQ
Q: What does S355J0 mean?
S stands for structural steel, 355 is the minimum yield strength in MPa, J denotes Charpy V-notch impact testing and 0 is the impact test temperature of 0 °C with 27 J minimum energy.
Q: Inside which standard is S355J0 specified?
The grade is specified in EN 10025-2, supported by the general delivery requirements of EN 10025-1. The material number is 1.0553.
Q: Is S355J0 an HSLA steel?
It is a non-alloy structural steel with a minimum yield strength of 355 MPa. Genuine micro-alloyed or fine grain steels are covered by other parts of the EN 10025 series.
Q: What is the difference between S355JR, S355J0 and S355J2?
All three share the same strength level. The difference lies in the Charpy impact test temperature: +20 °C, 0 °C and -20 °C respectively.
Q: Which delivery conditions can be supplied?
Hot rolled, normalized or thermomechanically controlled rolled. The condition is agreed at order stage and stated on the inspection document.
Q: Why does higher sulfur content improve machining but harm welding?
Sulfur forms inclusions that break the chip during machining, but it also reduces impact toughness and raises crack susceptibility, so it is unsuitable for welded pressure and structural plate.