What is S420N?
S420N is a high-strength, non-alloy structural steel grade standardized under EN 10025-3.
"S" = Structural steel
"420" = Minimum yield strength of 420 MPa
"N" = Supplied in normalized condition, providing uniform mechanical properties and good dimensional stability
S420N is widely used in heavy engineering, bridges, and structural applications where higher strength is required while maintaining excellent weldability and toughness.
1. Mechanical Properties
| Property | S420N Value / Requirement | Standard / Notes |
|---|---|---|
| Yield Strength (ReH) | ≥ 420 MPa | EN 10025-3 |
| Tensile Strength (Rm) | 520–680 MPa | EN 10025-3 |
| Elongation (A5) | ≥ 17% | Typical for high-strength steel |
| Impact Energy (Charpy V-notch) | ≥ 27 J at 20°C | Normalized condition |
| Hardness (HB) | 150–200 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 |
What is S355N?
S355N is a high-strength, non-alloy structural steel grade standardized under EN 10025-3.
"S" = Structural steel
"355" = Minimum yield strength of 355 MPa
"N" = Supplied in normalized condition, providing good weldability, toughness, and dimensional stability
It is widely used in bridges, building frameworks, and heavy engineering applications, offering higher strength than S275N while maintaining excellent weldability and reliability.
1. Mechanical Properties
| Property | S355N Value / Requirement | Standard / Notes |
|---|---|---|
| Yield Strength (ReH) | ≥ 355 MPa | EN 10025-3 |
| Tensile Strength (Rm) | 470–630 MPa | EN 10025-3 |
| Elongation (A5) | ≥ 20% | Typical for structural steel |
| Impact Energy (Charpy V-notch) | ≥ 27 J at 20°C | Normalized grade |
| 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 |
What is the difference of them?
| Feature | S355N | S420N |
|---|---|---|
| Yield Strength (ReH) | ≥ 355 MPa | ≥ 420 MPa |
| Tensile Strength (Rm) | 470–630 MPa | 520–680 MPa |
| Elongation (A5) | ≥ 20% | ≥ 17% |
| Impact Energy (Charpy V) | ≥ 27 J at 20°C | ≥ 27 J at 20°C |
| Weldability | Excellent | Excellent |
| Applications | Bridges, building frameworks, moderate-load structures | Bridges, heavy-duty structures, cranes, industrial frameworks |
Key Differences
Strength: S420N has a higher yield and tensile strength than S355N, enabling lighter and stronger structures for heavy-load applications.
Applications:
S355N: Suitable for moderate-load structural applications, such as standard buildings and bridges.
S420N: Preferred for heavy-duty structures, cranes, industrial machinery, and high-load frameworks.
Other Properties: Both grades share good weldability and toughness, but S420N provides a higher strength-to-weight ratio, reducing material requirements for the same load.
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.
