JIS G3106 — Marine steel plates for welded structures
Grades
SM400A, SM400B, SM400C, SM490A, SM490B, SM490C, SM490YA, SM490YB, SM520B, SM520C, SM570
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| SM400A | C≤0.23 (>100mm≤0.25), Mn≥2.5×C%, P≤0.035, S≤0.035 | Rm 400-510 MPa, Rp0.2 ≥245 MPa, A≥23% |
| SM400B | C≤0.20(>100mm≤0.22), Mn 0.60-1.40, P≤0.035, S≤0.035 | Rm 400-510 MPa, Rp0.2 ≥245 MPa, A≥23%, 0℃ Akv≥27J |
| SM400C | C≤0.18 (>100mm≤0.20), Mn≤1.40, P≤0.035, S≤0.035 | Rm 400-510 MPa, Rp0.2 ≥245 MPa, A≥23%, 0℃ Akv≥47J |
Application scope
JIS G3106 specifies hot-rolled steel plates for welded structures, widely used in the Japanese shipbuilding industry. Grades include SM400, SM490, SM520, SM570, and toughness levels A, B, and C. Standards emphasize carbon equivalent and impact toughness control to ensure weldability, specifying composition, tensile, and impact requirements. With a broad strength range, it is suitable for primarily welded ship hulls and marine machinery load-bearing structures.
Typical applications
Widely used in welded load-bearing components such as hulls, decks, bulkheads, and marine machinery structures of standard Japanese ships. Grades are classified according to strength and impact toughness, allowing selection based on stress and operating temperature; Grade C offers better low-temperature performance. With its excellent weldability and strength-toughness combination, it is suitable for ship structural engineering projects that extensively employ welding processes and have high requirements for joint quality and safety.
