SM400A, SM400B and SM400C steel plates are Japanese standard rolled steel for welding structure, S represents steel, M represents welding, 400 is also the lower limit tensile strength 400MPa, A is the steel plate grade, without impact, B is the steel plate grade, impact at 20℃, C is the steel plate grade, impact at 0℃.
Melting analysis of chemical composition of SM400A, SM400B and SM400C steel plates:
| Grade | Thickness | C | Si | Mn | P | S |
| SM400A | t≤50mm | ≤0.23 | - | ≥2.5 | ≤0.035 | ≤0.035 |
| 50<t≤200mm | ≤0.25 | |||||
| SM400B | t≤50mm | ≤0.20 | ≤0.35 | 0.60-1.50 | ≤0.035 | ≤0.035 |
| 50<t≤200mm | ≤0.22 | |||||
| SM400C | t≤100mm | ≤0.18 | ≤0.35 | 0.60-1.50 | ≤0.035 | ≤0.035 |
Mechanical properties of SM400A, SM400B and SM400C steel plates:
| Grade | Yield point or yield strength, N/m㎡ | Tensile strength | |||||
| Thickness mm | Thickness mm | ||||||
| ≤16 | 16<t≤40 | 40<t≤75 | 75<t≤100 | 100<t≤160 | 100<t≤200 | ≤100 | |
| SM400A | ≥245 | ≥235 | ≥215 | ≥215 | ≥205 | ≥195 | 400-510 |
| SM400B | ≥245 | ≥235 | ≥215 | ≥215 | ≥205 | - | 400-510 |
| SM400C | ≥245 | ≥235 | ≥215 | ≥215 | - | - | 400-510 |
SM400A, SM400B, and SM400C have the same base strength level, but differ in toughness levels for different working environments. Therefore, material selection should consider service temperature and structural safety requirements.
