SS400 (JIS G3101): Japanese General Structural Steel
JIS G3101 · Updated: 2026-05-24
SS400 is Japan's general-purpose rolled structural steel under JIS G3101, widely used across Asia-Pacific construction markets. The 'SS' prefix denotes structural steel, and '400' indicates minimum tensile strength of 400 MPa. Unlike A36 and S275, SS400 specifies tensile strength rather than yield strength as the primary mechanical requirement. It provides good weldability for general construction, shipbuilding, and bridge fabrication. Available as plates, sheets, strips, and sections from Japanese and Korean mills.
Quick Facts
| Category | Carbon Steel |
| Standard | JIS G3101 |
| Density | 7.85 g/cm³ |
| Yield Strength | 245 MPa (36 ksi) |
| Tensile Strength | 400-510 MPa (58-74 ksi) |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| ASTM A36 | Compare |
| Q235 | Compare |
| S275JR | Compare |
| E250 | Compare |
| St37-2 | Compare |
Related Materials
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Frequently Asked Questions
What is the key difference between SS400 and SM490?
SS400 is a general structural steel with a 400 MPa tensile requirement; SM490 (JIS G3106) is a higher-grade steel with 490 MPa minimum tensile and guaranteed yield strength. SM490 also requires impact testing (SM490A at 0°C, SM490B at +20°C) and is specified for welded structures and bridges. SS400 is for general construction; SM490 is for critical welded structures.