S355J0 and S420J0 are non-alloy structural steel grades specified under EN 10025-2, the European standard for hot-rolled structural steels . Both grades are characterized by their minimum yield strength (indicated by the number) and guaranteed impact toughness at 0°C (indicated by the "J0" suffix, requiring minimum 27J longitudinal Charpy V-notch energy) . They are supplied in hot-rolled, normalized, or controlled rolling conditions .
Key Differences:
Strength Level: S420J0 provides approximately 18% higher minimum yield strength (420 vs 355 MPa for ≤16mm), enabling weight reduction in structural designs.
Ductility: S355J0 offers superior elongation (20% vs 19% for ≤40mm), providing better formability.
Chemical Composition: S420J0 generally requires higher carbon equivalent to achieve its elevated strength, though specific EN 10025-2 limits for S420J0 carbon content are not explicitly detailed in the search results. S355J0's carbon maximum is strictly controlled at 0.20% for thinner sections .
Weldability: S355J0 exhibits better weldability due to lower carbon equivalent; S420J0 may require preheating for thicker sections and more careful welding procedure control.
Availability: S355J0 is widely available and commonly stocked globally; S420J0 is less common in the EN 10025-2 series, with S420 grade more frequently specified under EN 10025-3 (normalized) or EN 10025-4 (thermomechanical) for fine-grain variants .
Applications: S355J0 is extensively used in general structural fabrication, bridges, buildings, and machinery requiring guaranteed 0°C toughness . S420J0 is specified for higher-stressed components where enhanced strength justifies premium cost, though in practice, the fine-grain versions (S420N/NL or S420M/ML) are more commonly specified for demanding applications requiring both higher strength and assured weldability.
Chemical composition for S355J0 steel plate
| Main chemical elements composition of S355J0 steel plate | |||||||
| Thickness(mm) | C | Si | Mn | P | S | N | Cu |
| T≤16 | 0.20 | 0.55 | 1.60 | 0.030 | 0.030 | 0.012 | 0.55 |
| 16<T≤40 | 0.20 | ||||||
| 40<T | 0.22 | ||||||
Chemical composition for S420J0 steel plate
|
Grade |
Thk(mm) |
C |
Mn |
Si |
P |
S |
N |
Cu |
|
S420J0 |
≦40 |
0.2 |
1.7 |
0.55 |
0.03 |
0.03 |
0.025 |
0.55 |
|
>40 |
0.22 |
Mechnical property for S355J0 steel plate:
| Thickness (mm) | |||||||||
| S355J0 | ≤ 16 | > 16 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 ≤ 100 | > 100 ≤ 150 | > 150 ≤ 200 | > 200 ≤ 250 | > 250 |
| Yield strength (≥Mpa) | 355 | 345 | 335 | 325 | 315 | 295 | 285 | 275 | 275 |
| < 3 | ≥ 3 ≤ 100 | > 100 ≤ 150 | > 150 ≤ 250 | > 250 | |||||
| Tensile strength (Mpa) | 510-680 | 470-630 | 450-600 | 450-600 | 450-600 | ||||
Mechnical property for S420J0 steel plate:
| Grade |
Thk(mm) |
Yield Strength |
Tensile Strength |
Elongation in 2 in. |
|
MPa |
MPa |
% |
||
|
S420J0 |
≦16 |
450 |
550-720 |
17 |
|
>16, ≦100 |
410 |
|||
|
>100 |
380 |
530-700 |
