ASTM A36 vs Q235B
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
ASTM A36
Structural & HSLA Steel
ASTM A36 is the most widely used structural carbon steel in North America, the default material for buildings, bridges and general fabrication. Its chemistry limits relax as thickness grows, which is why A36 is a specification of minimum properties rather than a tight analysis.
Standards: DIN S235JR (near) · AISI A36 · JIS SS400 (near) · GB Q235B (near)
Q235B
Structural & HSLA Steel
Q235B is China’s everyday carbon structural steel — the volume grade for domestic construction, plate, sections and welded tube. Grade B adds a room-temperature impact test over the basic A quality, making it the default export offer in this strength class.
Standards: DIN S235JR (near) · AISI A36 (near) · JIS SS400 (near) · GB Q235B (GB/T 700)
Chemical composition compared (%)
| Element | ASTM A36 | Q235B |
|---|---|---|
| C | ≤0.25 (plate ≤20 mm) | 0.12–0.20 |
| Si | ≤0.40 | ≤0.30 |
| Mn | 0.80–1.20 (plate >20 mm) | 0.30–0.70 |
| P | ≤0.040 | ≤0.045 |
| S | ≤0.050 | ≤0.045 |
Properties compared
| Property | ASTM A36 | Q235B |
|---|---|---|
| Yield strength | ≥250 MPa | ≥235 MPa (≤16 mm) |
| Tensile strength | 400–550 MPa | 370–500 MPa |
| Elongation | ≥20% (200 mm) | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Impact | — | B grade: 27 J at 20 °C |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: ASTM A36 · Q235B. Substitution decisions for certified parts stay with the design authority.