S355G2+N is a normalized offshore structural steel plate certified under the European standard EN 10225 for use in fixed offshore structures, oil/gas platforms, and wind turbine foundations. It has a minimum yield strength of 355 MPa (for thickness ≤16mm) and tensile strength ranging from 470 to 630 MPa, with a minimum elongation of 22%. The "+N" designation indicates the normalized delivery condition, which refines the grain structure to improve toughness and weldability. This grade is impact tested at -20°C with a minimum energy requirement of 27 Joules, making it suitable for general offshore applications in moderate cold environments.
S355G3+N is also a normalized offshore structural steel certified under EN 10225, sharing the same minimum yield strength of 355 MPa and tensile strength range of 470-630 MPa. However, it offers enhanced low-temperature toughness compared to G2: while also impact tested at -20°C, it requires a higher minimum impact energy of 40 Joules, providing a greater safety margin against brittle fracture. To achieve this superior toughness, S355G3+N has stricter chemical composition controls, including lower carbon (≤0.18%) and sulfur (≤0.025%) limits. It is designed for more demanding offshore applications where higher reliability at cold temperatures is required.
Both S355G2+N and S355G3+N are normalized offshore structural steels under EN 10225 with identical strength (minimum yield 355 MPa) and delivery conditions (+N). Their primary difference lies in low-temperature impact toughness: G2 requires 27J at -20°C, suitable for general offshore applications, while G3 requires a higher 40J at the same temperature, offering superior resistance to brittle fracture for more critical structures. This enhanced performance in G3 is achieved through stricter chemical composition controls, including lower carbon and sulfur content. The selection between them depends on whether the project requires standard toughness (G2) or enhanced safety margins for cold environments (G3).
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:
Grade | S355G3+N steel mechanical property | |||
Tensile Strength (MPa) | Yield Strength (MPa) | % Elongation in 2 in.(50mm) min | ImpactingTest Temperature (°C) | |
S355G3+N | 470-630 | 350-320 | 22 | -40 |
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
C | Si | Mn | P | S | Cr | Mo |
0.18 | 0.50 | 0.90-1.65 | 0.030 | 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 |
