JIS G3125 — Weather-resistant high-strength hot-rolled steel plates and strips
Grades
SPA-H, SPA-C
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| SPA-H | C≤0.12, Mn≤0.60, P 0.07-0.15, S≤0.035, Si 0.25-0.75, Cr 0.30-1.25, Cu 0.25-0.55, Ni≤0.65 | Rm ≥480 MPa, Rp0.2 ≥345 MPa, A≥22%, weather resistance |
| SPA-C | C≤0.12, Mn≤0.60, P 0.07-0.15, S≤0.035, Si 0.25-0.75, Cr 0.30-1.25, Cu 0.25-0.55, Ni≤0.65 | Rm ≥450 MPa, Rp0.2 ≥315 MPa, A≥26%, weather resistance |
Application scope
JIS G3125 specifies high-strength hot-rolled steel plates and strips with high resistance to atmospheric corrosion, available in SPA-H and SPA-C grades, suitable for welded and cold-formed weather-resistant components. Utilizing a higher phosphorus, copper, chromium, and silicon content, a dense and stable rust layer is formed on the surface, resulting in superior weather resistance compared to general weather-resistant steels, allowing for exposed service. Products are delivered as hot-rolled plates and strips, balancing strength, formability, and corrosion resistance, suitable for vehicles and exposed structures.
Typical applications
Widely used in corrosion-resistant components such as container side panels, top panels, and underframes, as well as railway freight car bodies, open wagons, and hopper car structures. Due to its excellent atmospheric corrosion resistance and formability, it is also used in long-term exposed components such as building curtain walls, exterior wall panels, outdoor facilities, and landscaping. Suitable for transportation equipment and exposed structures frequently exposed to wind, rain, and salt spray erosion, where a stable rust layer is desired for paint-free protection.
