S355K2 is a non-alloy high-strength structural steel standardized under EN 10025-2.
"S" = Structural steel
"355" = Minimum yield strength of 355 MPa
"K2" = Charpy impact energy of 40 J at −20°C, providing excellent low-temperature toughness
It is widely used in bridges, offshore structures, heavy engineering, and cold-environment construction where both high strength and low-temperature impact resistance are required.
1. Mechanical Properties
| Property | S355K2 Value / Requirement | Standard / Notes |
|---|---|---|
| Yield Strength (ReH) | ≥ 355 MPa | EN 10025-2 |
| Tensile Strength (Rm) | 470–630 MPa | EN 10025-2 |
| Elongation (A5) | ≥ 20% | Typical for structural steel |
| Impact Energy (Charpy V-notch) | ≥ 40 J at −20°C | "K2" rating |
| Hardness (HB) | 140–190 HB | Brinell hardness |
| Density | 7.85 g/cm³ | Standard steel value |
| Modulus of Elasticity | 210 GPa | Typical for structural steel |
2. Chemical Composition (Typical % by weight)
| Element | C | Si | Mn | P | S | N |
|---|---|---|---|---|---|---|
| % | 0.22 | ≤0.55 | 1.60 | ≤0.035 | ≤0.035 |
≤0.012 |
Is S355J2 better than S355K2?
S355J2 vs S355K2
| Feature | S355J2 | S355K2 |
|---|---|---|
| Yield Strength (ReH) | ≥ 355 MPa | ≥ 355 MPa |
| Tensile Strength (Rm) | 470–630 MPa | 470–630 MPa |
| Impact Energy (Charpy V) | ≥ 27 J at −20°C | ≥ 40 J at −20°C |
| Low-Temperature Use | Cold environments | Very cold/cold-sensitive environments |
| Weldability | Excellent | Excellent |
| Typical Applications | Bridges, buildings, offshore in cold climates | Bridges, offshore, heavy engineering, extremely low-temperature structures |
Key Differences
Impact Toughness:
S355J2: 27 J at −20°C
S355K2: 40 J at −20°C → significantly higher toughness
Applications:
S355J2 is suitable for general cold-environment structural steel
S355K2 is preferred for critical structures, offshore platforms, or areas exposed to extreme cold
Other Properties:
Both grades have the same yield and tensile strength, machinability, and weldability.
S355K2 provides extra safety in low-temperature impact-critical applications.
What is the ASTM material equivalent to S355K2?
Notes:
Both are high-strength, non-alloy structural steels with similar minimum yield strength (~355 MPa).
S355K2 has enhanced low-temperature toughness (Charpy impact 40 J at −20°C), while ASTM A572 Grade 50 usually specifies impact energy at room temperature or lower, depending on thickness.
Exact chemical composition and impact energy may differ slightly, so verification is recommended for critical low-temperature applications.
GNEE Steel also supplies a variety of high-strength steel plates, such as A514 Grade F, A572 Grade 50, A588 Grade A, S355JR, S690Q, SS400, S690QL, Q345B, Q345E, etc. If you want to know more about other types of steel plates, you can call the consultation hotline at +8615824687445 or send an email to info@gneesteels.com. You are welcome to consult us, and we are very willing to answer your questions.
