What Is JIS G 3125 SPA-H Steel?
SPA-H is an atmospheric corrosion resistant hot-rolled steel per JIS G3125, one of the most widely used "Corten-type" weathering steels in Asia. Its atmospheric corrosion resistance is substantially better than carbon steel with or without copper addition, thanks to the high-phosphorus copper-chromium composition that forms a protective rust layer under atmospheric exposure.
Chemical Composition (JIS G3125, %)
| Element | Content |
|---|---|
| Carbon (C) | ≤ 0.12 |
| Silicon (Si) | 0.20–0.75 |
| Manganese (Mn) | ≤ 0.60 |
| Phosphorus (P) | 0.070–0.150 |
| Sulfur (S) | ≤ 0.035 |
| Copper (Cu) | 0.25–0.55 |
| Chromium (Cr) | 0.30–1.25 |
| Nickel (Ni) | ≤ 0.65 |
Mechanical Properties (Indicative per JIS G3125)
| Thickness | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|
| ≤ 6.0 mm | ≥ 355 | ≥ 490 | ≥ 22 |
| > 6.0 mm | ≥ 355 | ≥ 490 | ≥ 15 |
Confirm the elongation values against the current JIS G3125 edition (values vary with gauge length and thickness).
Equivalents (For Reference Only)
| Standard | Grade |
|---|---|
| EN 10025-5 | S355J0WP (1.8945) |
| AFNOR | E36WA3 |
| BS | WR50A, WR50B, WR50C |
| GB/T 4171 | 09CuPCrNi-A |
| ISO | Fe355W-1A |
Equivalents are for reference only; verify impact requirements and chemistry before substitution.
Applications
Air preheaters, economizers, bridge building, construction, railway carriages and container production - outdoor structures where the self-protecting patina reduces maintenance.
FAQ
Q: What does SPA-H stand for?
A: It is the JIS G3125 designation for hot-rolled steel with superior atmospheric corrosion resistance (H = hot-rolled grade; SPA-C is the cold-rolled grade).
Q: What is the difference between SPA-H and S355J0WP?
A: They are equivalent weathering grades of the Japanese and European systems with similar chemistry (high phosphorus, copper, chromium); verify impact classes and delivery requirements before substitution.
Q: Is SPA-H weldable?
A: Yes, with standard procedures; weathering-grade consumables are recommended for matching corrosion behavior at the weld.
Q: Does SPA-H need painting?
A: No - outdoors it forms a protective patina and can be used bare; painting is optional for aesthetics or aggressive environments.
We offer customized processing services. If you would like to learn more about JIS G 3125 SPA-H, please feel free to contact Gnee Steel; our team will respond within two hours.
