The main difference between S420G1+M and S460G1+M steel plates lies in their strength, with S460 offering higher guaranteed yield strength (around 460 MPa) compared to S420 (around 420 MPa), while both are weldable, fine-grained structural steels used in offshore structures, designated by the '+M' for Thermo-Mechanically Rolled (TMCP) delivery condition for good weldability and toughness, though S460 typically has tighter chemical compositions for enhanced properties.
Mechnical property for S420G1+M steel plate:
| Thickness (mm) | |||||
| S420G1+M | ≤ 16 | > 16 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 |
| Yield strength (≥Mpa) | 420 | 400 | 390 | 380 | 380 |
| ≤ 40 | > 40 | ||||
| Tensile strength (Mpa) | 500 | 480 | |||
Mechnical property for S460G1+M steel plate:
| Thickness (mm) | ||||||
| S460G1+M steel plate | ≤ 16 | > 16 ≤ 25 | > 25 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 |
| Yield strength (≥Mpa) | 460 | 440 | 420 | 415 | 405 | 400 |
| Tensile strength (Mpa) | 540-700 | 530-690 | 520-680 | 515-675 | 505-665 | 500-660 |
Chemical composition for S420G1+M steel plate
| Main chemical elements composition of S420G1+M steel plate | ||||||||
| C | Si | Mn | P | S | Cr | Mo | Nb+V | Nb+V+Ti |
| 0.14 | 0.15-0.55 | 1.65 | 0.020 | 0.010 | 0.25 | 0.25 | 0.09 | 0.11 |
| Ni | Alt | Cu | N | Nb | Ti | V | Cr+Mo+Ni+Cu | |
| 0.70 | 0.015-0.055 | 0.30 | 0.010 | 0.040 | 0.025 | 0.080 | 0.90 | |
Chemical composition for S460G1+M steel plate
| Main chemical elements composition of S460G1+M steel plate | ||||||||
| C | Si | Mn | P | S | Cr | Mo | Nb+V | Nb+V+Ti |
| 0.14 | 0.15-0.55 | 1.65 | 0.020 | 0.010 | 0.25 | 0.25 | 0.09 | 0.11 |
| Ni | Alt | Cu | N | Nb | Ti | V | Cr+Mo+Ni+Cu | |
| 0.70 | 0.015-0.055 | 0.30 | 0.010 | 0.040 | 0.025 | 0.080 | 0.90 | |
Key Differences
Strength Designation (S420 vs. S460):
S420G1+M: Minimum Yield Strength of approximately 420 MPa (megapascals).
S460G1+M: Minimum Yield Strength of approximately 460 MPa (megapascals).
This numerical prefix directly indicates the minimum guaranteed yield strength, making S460 stronger.
G1 (Grade/Application): Both are classified as offshore structural steels, designed for demanding applications like oil rigs and platforms, offering good ductility and weldability.
+M (Delivery Condition):
'+M' signifies a Thermo-Mechanically Controlled Process (TMCP) or Thermo-Mechanically Rolled (M) condition.
This process involves controlled rolling and cooling, resulting in fine grain structure, which enhances strength, toughness, and weldability without needing extensive quenching and tempering, making them suitable for thick plates.
