S355G2+N and S355G3+N are both offshore structural steel grades under EN 10225 standard, offering 355 MPa yield strength, but differ in their impact toughness requirements (charpy V-notch), with G3 generally requiring higher energy absorption at lower temperatures than G2, making G3 better for colder/more demanding offshore environments, though both provide normalized (N) properties for weldability and strength.
Mechnical property for S355G2+N steel plate
| Thickness (mm) | |||||||
| S355G2+N | ≤ 16 | > 16 ≤ 25 | > 25 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 100 | > 100 | |
| Yield strength (≥Mpa) | 355 | 345 | 345 | 345 | 345 | 345 | |
| ≤ 100 | > 100 | ||||||
| Tensile strength (Mpa) | 470-630 | 470-630 | |||||
Mechnical property for S355G3+N steel plate
| Thickness | Mechanical properties | |
| ≤16mm | ReH(MPa) | ≥355 |
| Rm(MPa) | 470-630 | |
| A(%) | ≥22 | |
| >16-40mm | ReH(MPa) | ≥345 |
| Rm(MPa) | 470-630 | |
| A(%) | ≥22 |
Chemical composition for S355G2+N steel plate
| Main chemical elements composition of S355G2+N steel plate | ||||||
| C | Si | Mn | P | S | Cr | Mo |
| 0.20 | 0.50 | 0.90-1.65 | 0.035 | 0.030 | 0.30 | 0.10 |
| Ni | Alt min. | Cu | N | Nb | Ti | V |
| 0.50 | 0.020 | 0.35 | 0.015 | 0.060 | 0.030 | 0.12 |
Chemical composition for S355G3+N steel plate
| Main chemical elements composition of S355G3+N steel plate | ||||||
| C | Si | Mn | P | S | Cr | Mo |
| 0.18 | 0.50 | 0.90-1.65 | 0.03 | 0.025 | 0.30 | 0.10 |
| Ni | Alt min. | Cu | N | Nb | Ti | V |
| 0.50 | 0.020 | 0.35 | 0.015 | 0.060 | 0.030 | 0.12 |
Key Differences
G2 vs. G3 (Toughness): The 'G' series in EN 10225 denotes grades for offshore structures, and the number (2, 3, 7, 10) indicates increasing levels of toughness, especially at lower temperatures.
S355G2+N: Meets minimum impact energy requirements, suitable for general offshore applications.
S355G3+N: Offers improved impact toughness (higher energy absorption) at colder temperatures, making it better for more severe conditions.
+N (Normalized): Both steels are supplied in the normalized condition, meaning they undergo a specific heat treatment (normalizing) for uniform grain structure, improving ductility and weldability, crucial for large plates used in offshore construction.
Chemical Composition: While strength (S355) and processing (+N) are similar, the G3 grade's enhanced toughness often involves tighter control over elements like carbon and manganese, but the main differentiator is the Charpy impact test results.
