ASTM A588 vs SPA-H
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 A588
Structural & HSLA Steel
ASTM A588 is the American HSLA weathering steel specification — the 50 ksi structural grade whose Cu-Cr-Ni alloying gives roughly four times the atmospheric corrosion resistance of plain carbon steel. Unpainted A588 bridges are a standard sight across North America.
Standards: DIN S355J2W (near) · AISI A588 Gr.A · GB Q355NH (near)
SPA-H
Structural & HSLA Steel
SPA-H is the JIS G3125 hot-rolled weathering steel — Japan’s Corten A equivalent, mass-produced for containers, vehicles and architecture. Its Cu-Cr-Ni-P analysis mirrors the original US Steel weathering composition.
Standards: DIN S355J0WP type (near) · AISI A242 type (near) · JIS SPA-H (JIS G3125) · GB 09CuPCrNi-A (near)
Chemical composition compared (%)
| Element | ASTM A588 | SPA-H |
|---|---|---|
| C | ≤0.19 (Gr.A) | ≤0.12 |
| Si | 0.30–0.65 (Gr.A) | 0.25–0.75 |
| Mn | 0.80–1.25 (Gr.A) | ≤0.60 |
| P | ≤0.040 | 0.070–0.150 |
| S | ≤0.050 | ≤0.035 |
| Cr | 0.40–0.65 (Gr.A) | 0.30–1.25 |
| Ni | ≤0.40 (Gr.A) | ≤0.65 |
| Cu | 0.25–0.40 (Gr.A) | 0.25–0.55 |
| V | 0.02–0.10 (Gr.A) | — |
Properties compared
| Property | ASTM A588 | SPA-H |
|---|---|---|
| Yield strength | ≥345 MPa (≤100 mm) | ≥355 MPa |
| Tensile strength | ≥485 MPa (≤100 mm) | ≥490 MPa |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
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 A588 · SPA-H. Substitution decisions for certified parts stay with the design authority.