S355J2 is a widely used European standard (EN 10025-2) high-strength, low-carbon structural steel. It is characterized by its excellent weldability, toughness, and high yield strength.
Key Specifications & Meaning
The designation "S355J2" breaks down as follows:
S: Indicates Structural steel.
355: Represents the minimum Yield Strength of 355 MPa (for thicknesses ≤ 16mm).
J2: Specifies Impact Toughness. It must reach a minimum of 27 Joules during a Charpy V-notch impact test at -20°C.
1.0577: The numeric material number assigned under the EN system.
Mechanical & Physical Properties
Tensile Strength: Typically ranges from 470 to 630 MPa.
Weldability: Highly weldable with a maximum Carbon Equivalent Value (CEV) of approximately 0.47.
Common Delivery Conditions: Often supplied as S355J2+N, where "+N" indicates it has been normalized (rolled or heat-treated to a normalized state) to improve grain structure and toughness.
Common Applications
Due to its strength-to-weight ratio and durability in low temperatures, it is used in:
Civil Engineering: Bridges, buildings, and transmission towers.
Heavy Machinery: Cranes, excavators, mining equipment, and trailers.
Maritime/Energy: Offshore structures, shipbuilding, and wind turbines.
Industrial: Pressure vessels, railway axles, and connecting rods.
Global Equivalents
While not identical, S355J2 is often compared to the following international grades:
USA (ASTM): A572 Grade 50 is the closest equivalent.
UK (Former BS): 50D.
Germany (Former DIN): St52-3.
China (GB): Q355D or Q345D.
Chemical composition % of steel S355J2 (1.0577): EN 10025-2-2004
| Nominal thickness =< 40(mm) C max = 0.20 Nominal thickness =< 30(mm) CEV max = 0.45 |
| C | Si | Mn | P | S | Cu | CEV |
| max 0.22 | max 0.55 | max 1.6 | max 0.03 | max 0.03 | max 0.55 | max 0.47 |
The closest and most commonly accepted US equivalent of S355J2 is ASTM A572 Grade 50. However, due to fundamental differences in standards philosophy, they are not a perfect 1:1 equivalent. The equivalence is primarily based on strength, while key differences exist in mandatory toughness requirements.
Here is a detailed comparison and guidance for substitution:
Core Comparison: S355J2 vs. ASTM A572 Grade 50
| Feature | S355J2 (EN 10025-2) | ASTM A572 Grade 50 | Implication for Equivalency |
|---|---|---|---|
| Yield Strength | 355 MPa (for t ≤ 16mm) | 345 MPa (50 ksi) | Close Match. The 10 MPa difference is negligible for most designs. |
| Tensile Strength | 470 - 630 MPa (for t ≤ 40mm) | ≥ 450 MPa (65 ksi min.) | Overlapping ranges; A572 Gr. 50 meets the S355J2 minimum. |
| Impact Toughness | Mandatory. 27 J at -20°C (Charpy V-notch). | Not mandatory. Required only if Supplementary Requirement S5 is specified. | Critical Difference. S355J2 has guaranteed low-temperature toughness; standard A572 Gr. 50 does not. |
| Standard Philosophy | Product/Application Standard. Toughness is an integral part of the material grade. | Material-Centric Standard. Toughness is an optional, purchasable add-on. | To be equivalent, A572 must be ordered with specific supplementary requirements. |
| Chemical Composition | Limits for C, Mn, P, S, Si, and a maximum Carbon Equivalent (CEV) for weldability. | Limits for C, Mn, P, S, and micro-alloys (V, Nb, etc.). No mandatory CEV. | Both are designed for weldability, but S355J2's CEV provides a direct weldability indicator. |
Other Potential US Grades (Contextual Equivalents)
ASTM A992: This is the standard specification for structural steel shapes (W-beams) in the US. Its required yield strength is 50 ksi (345 MPa) and it mandates a maximum yield-to-tensile ratio and a minimum Charpy toughness of 20 ft-lbf at 70°F. However, its toughness is tested at a much higher temperature than S355J2, so it is not a direct substitute for low-temperature applications. For building frames in moderate climates, A992 is often the functional shape equivalent.
ASTM A709 Grade 50: Used for bridge construction. It has various toughness grades (e.g., Grade 50T2 for -20°F impact testing), making it a direct match for S355J2 in bridge applications, but it is not a general structural steel.
Conclusion
For general strength-based design in moderate climates, ASTM A572 Grade 50 is considered the direct US equivalent.
For applications requiring the guaranteed low-temperature toughness of S355J2, you must specify ASTM A572 Grade 50 with Supplementary Requirement S5 for impact testing at the appropriate temperature.
For structural shapes in building frames, ASTM A992 is the default material but must be evaluated for toughness requirements.
Always consult the project's governing design code (AISC, Eurocode) and a structural engineer before making a material substitution to ensure all service and safety requirements are met.
1. What Is S355J2 Steel?
S355J2 is a European standard structural steel with a minimum yield strength of 355 MPa and guaranteed impact toughness of 27 Joules at -20°C, making it suitable for low-temperature applications.
2. What Is The Difference Between S355J0 And S355J2?
The key difference is the impact test temperature. S355J0 is tested at 0°C, while S355J2 is tested at -20°C, giving S355J2 better low-temperature toughness for colder environments.
3. What Does The 'J2' Mean In S355J2?
The 'J2' indicates the steel's impact toughness grade. 'J' means the minimum Charpy V-notch impact energy is 27 Joules, and '2' signifies the test is conducted at -20°C.
4. What Is The Yield Strength Of S355J2?
The minimum yield strength is 355 MPa for thicknesses up to 16mm, but it decreases for thicker sections (e.g., 345 MPa for 16-40mm, 335 MPa for 40-63mm) as per EN 10025-2.
5. Is S355J2 Equivalent To ASTM A572 Grade 50?
They are generally comparable in strength, but S355J2 has a mandatory toughness requirement at -20°C, while ASTM A572 Gr. 50 requires impact testing only if specified by the purchaser.
6. Can S355J2 Be Welded?
Yes, S355J2 has good weldability. However, proper procedures-such as using suitable low-hydrogen electrodes and applying preheat for thicker sections-must be followed to maintain its mechanical properties.
7. What Is S355J2+N?
The '+N' means the steel is supplied in a normalized or normalized rolled condition. This process refines the grain structure, improving toughness and making the steel more forgiving for welding, especially in thicker sections.
8. What Are The Chemical Properties Of S355J2?
S355J2 has controlled levels of carbon, manganese, silicon, phosphorus, and sulfur. Its maximum Carbon Equivalent (CEV) is also limited, typically around 0.40-0.45, to ensure good weldability.
9. What Is The Tensile Strength Of S355J2?
For common thicknesses (≤ 40mm), the tensile strength ranges from 470 MPa to 630 MPa, as specified in the EN 10025-2 standard.
10. Where Is S355J2 Steel Used?
It's widely used in structural applications exposed to colder climates, such as bridges, building frames, offshore structures, cranes, and heavy equipment where low-temperature toughness is critical.
11. What Is The Density Of S355J2?
Like most structural carbon steels, the density of S355J2 is approximately 7,850 kg/m³ (or 7.85 g/cm³).
12. Is S355J2 Corrosion Resistant?
No, S355J2 is not a corrosion-resistant (weathering) steel. It is a carbon steel that will rust if exposed to the elements unless protected by paint, galvanizing, or other coatings.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
