SM490A vs S355J2
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.
SM490A
Structural & HSLA Steel
SM490A is the weldable structural steel of JIS G3106 — rolled steel for welded structures with controlled chemistry (C ≤0.20%, Mn ≤1.60%) and a 490–610 MPa tensile range. It is the Japanese counterpart class to Q345B and A572 Gr.50 and the default upgrade from SS400 for welded primary structures.
Standards: DIN 1.0570 (S355J2, near) · AISI A572 Gr.50 (near) · JIS SM490A (JIS G3106) · GB Q345B (near)
S355J2
Pipe & Tube Steel
S355J2 is Europe’s structural HSLA steel (EN 10025-2), the benchmark for welded structures, machinery and pipe where −20 °C toughness is specified.
Standards: DIN 1.0577 (S355J2) / 1.0570 legacy St52-3 · AISI A572 Gr.50 (near) · JIS SM490B (near) · GB Q345B (near)
Chemical composition compared (%)
| Element | SM490A | S355J2 |
|---|---|---|
| C | ≤0.20 | ≤0.20 |
| Si | ≤0.55 | ≤0.55 |
| Mn | ≤1.60 | ≤1.60 |
| P | ≤0.035 | ≤0.025 |
| S | ≤0.035 | ≤0.025 |
Properties compared
| Property | SM490A | S355J2 |
|---|---|---|
| Tensile strength | 490–610 MPa | 470–630 MPa |
| Yield strength | ≥325 MPa (≤16 mm) | ≥355 MPa (≤16 mm) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Impact | A grade: no mandatory Charpy (B/C grades add impact requirements) | J2: −20 °C, ≥27 J |
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: SM490A · S355J2. Substitution decisions for certified parts stay with the design authority.