SS400
Data verifiedSS400 is Japan’s general structural steel under JIS G3101 and one of the most traded structural grades in Asia. The “400” is its minimum tensile class (400–510 MPa); the standard caps only phosphorus and sulfur and leaves carbon and manganese to the mill, so SS400 is bought on mechanical properties, not chemistry.
Chemical composition
| Element | Content (%) |
|---|---|
| P | ≤0.050 |
| S | ≤0.050 |
| C / Si / Mn | Not specified by JIS G3101 — the grade is defined by its tensile properties, not by chemistry |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Tensile strength | 400–510 MPa |
| Yield strength | ≥245 MPa (≤16 mm) |
| Density | 7.85 g/cm³ |
| Weldability | Excellent in practice (chemistry uncontrolled beyond P/S) |
Heat treatment
None — used hot rolled. No quench-and-temper response; do not specify SS400 where guaranteed hardenability or impact toughness is required.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.0038 (S235JR, near) |
| aisi | A36 (near) |
| jis | SS400 (JIS G3101) |
| gb | Q235B (near) |
Compare side by side: SS400 vs ASTM A36 · SS400 vs S235JR · SS400 vs SS490
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Building frames, bridges, general fabrication, base plates, channels and angles, non-critical machinery structures.
Processing: Excellent weldability and formability in practice; mills keep carbon low enough for routine welding, but verify the mill certificate CEV for thick or restrained joints.
FAQ
- Is SS400 the same as ASTM A36?
- Near-equivalent: both are ~245 MPa yield general structural steels with 400–510/400–550 MPa tensile ranges. A36 caps carbon by thickness while SS400 does not control carbon at all — check the certificate when a drawing names one standard only.
- Does SS400 guarantee impact toughness?
- No. JIS G3101 sets no Charpy requirement for SS400. For guaranteed low-temperature toughness specify an SM grade (JIS G3106) or an EN S355 J-grade.
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Ask for a quotationVisit NasteelSource: JIS G3101 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.