What is S420M?
S420M is a thermo-mechanically rolled, fine-grain high-strength structural steel specified in EN 10025-4.
It provides:
Minimum yield strength: 420 MPa
Excellent toughness and ductility
Good weldability and formability
The "M" designation indicates thermo-mechanically rolled steel, offering consistent mechanical properties and better toughness than standard normalized grades. S420M is widely used in bridges, offshore structures, cranes, heavy machinery, and structural engineering applications.
1. Chemical Composition (Typical Values, %)
| Element | C (max) | Si | Mn | P (max) | S (max) | Nb | V | Ti |
|---|---|---|---|---|---|---|---|---|
| S420M | 0.22 | ≤ 0.55 | 1.00–1.60 | 0.025 | 0.020 | ≤ 0.06 | ≤ 0.12 | ≤ 0.03 |
2. Mechanical Properties
| Property | Value |
|---|---|
| Yield Strength (≤16 mm) | 420 MPa |
| Yield Strength (40–100 mm) | 400–420 MPa |
| Tensile Strength | 520–680 MPa |
| Elongation (A5) | ≥ 20–22% |
| Charpy Impact | ≥ 27 J at –20°C |
| Density | 7.85 g/cm³ |
What is the tensile strength of S420M?
The tensile strength of S420M typically ranges from 520 to 680 MPa, depending on plate thickness and processing.
Yield Strength: Minimum 420 MPa (≤16 mm)
Tensile Strength: 520–680 MPa
Elongation (A5): ≥ 20–22%
Impact Toughness: ≥ 27 J at –20°C
S420M combines high strength, toughness, and weldability, making it suitable for bridges, offshore structures, cranes, and heavy engineering applications.
The tensile strength of S420M steel varies with thickness, but is typically between 480 and 680 MPa. For example, when the thickness is no more than 16 mm, the tensile strength ranges from 520 to 680 MPa; while for thicknesses between 40 and 63 mm, the range is 500 to 660 MPa. Thickness ≤ 16 mm: tensile strength 520 to 680 MPa. Thickness > 16 mm and ≤ 40 mm: tensile strength 520 to 680 MPa. Thickness > 40 mm and ≤ 63 mm: tensile strength 500 to 660 MPa. Thickness > 63 mm and ≤ 80 mm: tensile strength 480 to 640 MPa.
Does S420M require ultrasonic or radiographic testing?
S420M does not inherently require ultrasonic (UT) or radiographic (RT) testing under the EN 10025-4 standard for general delivery.
Details:
EN 10025-4 specifies mechanical and chemical properties, but non-destructive testing (NDT) like UT or RT is only required if specified by the customer or project.
For critical structural applications (e.g., offshore platforms, bridges, pressure vessels), clients may require UT or RT to detect internal defects or inclusions.
Standard S420M plates are typically supplied with mill test certificates (EN 10204 3.1 or 3.2) verifying chemical composition and mechanical properties.
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.
