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.
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 |
S355J2 is generally considered the closest European equivalent to ASTM A572 Grade 50, and they are often used interchangeably in international projects, but they are not exactly identical. The equivalence is primarily based on strength, while key differences exist in toughness requirements, standards philosophy, and testing.
Here's a detailed comparison:
Core Similarities (Why They Are Often Substituted)
| Feature | S355J2 (EN 10025-2) | ASTM A572 Grade 50 | Practical Implication |
|---|---|---|---|
| Yield Strength | 355 MPa (for t ≤ 16mm) | 345 MPa (50 ksi) | The 10 MPa difference is negligible in most designs. |
| Material Type | High-strength low-alloy (HSLA) structural steel. | High-strength low-alloy (HSLA) structural steel. | Same family of materials. |
| Common Applications | Bridges, buildings, heavy equipment. | Bridges, buildings, heavy equipment. | Used for similar structural purposes. |
Critical Differences (Why They Are Not Fully Identical)
| Feature | S355J2 | ASTM A572 Gr. 50 | Practical Implication |
|---|---|---|---|
| 1. Impact Toughness | Mandatory. The "J2" requires Charpy V-notch testing at -20°C with a minimum 27 Joules. | Not mandatory by default. Impact testing is required only if specified by the purchaser (e.g., via Supplementary Requirement S5). | This is the biggest difference. S355J2 guarantees low-temperature toughness; A572 Gr.50 does not unless explicitly ordered. |
| 2. Standard Philosophy | EN (European) standards are product/application-centric. The grade includes mandatory toughness. | ASTM (U.S.) standards are material-centric. The base specification focuses on chemistry and tensile properties. | EN grades often provide more built-in performance guarantees. |
| 3. Chemical Composition | Has a maximum Carbon Equivalent (CEV) limit to ensure weldability. Specific alloying approach. | Has defined limits for C, Mn, P, S, and micro-alloys (e.g., V, Nb). No mandatory CEV calculation. | S355J2's CEV provides a direct weldability indicator. |
| 4. Delivery Condition | Typically supplied in the as-rolled condition for J2. "+N" (normalized) is a separate, superior grade. | Typically supplied as-rolled. | |
| 5. Product Forms | Governed by separate product standards: • Plates: EN 10025-2 • Sections (e.g., I-beams): EN 10210-1 |
Covers plates, shapes, and bars within the single ASTM A572 specification. | Must ensure the correct product form standard is referenced. |
How to Specify a True Equivalent
To make a proper substitution, you must match all critical design requirements, not just yield strength.
To replace ASTM A572 Gr. 50 with a European steel: Use S355J2 from the correct product standard. For example:
For plates: EN 10025-2: S355J2
For hot-finished structural hollow sections: EN 10210-1: S355J2H
Note: S355J2 provides a toughness advantage that may not be required by the original A572 spec.
To replace S355J2 with an American steel: Specify ASTM A572 Grade 50 PLUS the Supplementary Requirement S5 (Charpy V-notch impact test), specifying a test temperature of -20°F (approx. -29°C) and an energy level of 20 ft-lbf (approx. 27 J) to match or exceed the J2 property.
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.
