What is difference between the SPA-H and SPA-C Steel?
SPA-H and SPA-C are weathering structural steels under JIS G3125, with SPA-H offering higher strength and load-bearing capacity. SPA-H provides a yield strength of ≥355 MPa and tensile strength of 490–610 MPa, making it suitable for heavy-duty applications such as shipping containers, where it withstands stacking loads, vibration, and repeated lifting with reduced deformation and fatigue risks.
SPA-C offers a lower strength level with a yield strength of ≥295 MPa, while maintaining good weather resistance, weldability, and formability.
Both grades contain Cu, Cr, and Ni alloying elements, forming a stable protective patina layer with atmospheric corrosion resistance approximately 4–8 times higher than ordinary carbon steel.
What is SPA-H Weathering Steel?
SPA-H weathering steel is a high-strength atmospheric corrosion-resistant steel specified under JIS G3125. With alloying elements such as Cu, Cr, and Ni, it forms a dense protective patina layer that provides excellent resistance to marine salt spray, moisture, and atmospheric corrosion.
Featuring a yield strength of ≥355 MPa and tensile strength of 490–610 MPa, SPA-H combines high strength, durability, and fatigue resistance, making it ideal for shipping containers, railway vehicles, bridges, and other heavy-duty outdoor structures.
What is SPA-C Weathering Steel?
SPA-C weathering steel is an atmospheric corrosion-resistant structural steel specified under JIS G3125. It contains weathering alloying elements such as copper, chromium, and nickel, which form a dense and stable protective patina layer on the steel surface.
With a yield strength of ≥295 MPa and tensile strength of ≥400 MPa, SPA-C offers good weather resistance, weldability, and formability, making it suitable for architectural structures, bridges, railway facilities, industrial equipment, and other outdoor applications requiring long-term durability.
Chemical Composition Comparison of SPA-H and SPA-C Weathering Steel
| Element | SPA-H (%) | SPA-C (%) |
|---|---|---|
| Carbon (C) | ≤0.12 | ≤0.12 |
| Silicon (Si) | ≤0.75 | ≤0.75 |
| Manganese (Mn) | ≤1.00 | ≤1.00 |
| Phosphorus (P) | ≤0.035 | ≤0.035 |
| Sulfur (S) | ≤0.035 | ≤0.035 |
| Copper (Cu) | 0.25–0.55 | 0.20–0.50 |
| Chromium (Cr) | 0.30–1.25 | 0.30–1.25 |
| Nickel (Ni) | 0.12–0.65 | ≤0.65 |
Physical Properties Comparison of JIS G3125 SPA-H and SPA-C Weathering Steel
| Property | SPA-H | SPA-C |
|---|---|---|
| Density | Approx. 7.85 g/cm³ | Approx. 7.85 g/cm³ |
| Melting Point | Approx. 1,450–1,520°C | Approx. 1,450–1,520°C |
| Elastic Modulus | Approx. 200 GPa | Approx. 200 GPa |
| Thermal Conductivity | Approx. 40–50 W/(m·K) | Approx. 40–50 W/(m·K) |
| Specific Heat Capacity | Approx. 460–500 J/(kg·K) | Approx. 460–500 J/(kg·K) |
| Poisson's Ratio | Approx. 0.30 | Approx. 0.30 |
| Thermal Expansion Coefficient | Approx. 11.7 × 10⁻⁶ /°C | Approx. 11.7 × 10⁻⁶ /°C |
| Atmospheric Corrosion Resistance | Approx. 4–8 times higher than carbon steel | Approx. 4–8 times higher than carbon steel |
Mechanical Properties Comparison of JIS G3125 SPA-H and SPA-C Weathering Steel
| Property | SPA-H | SPA-C |
|---|---|---|
| Yield Strength | ≥355 MPa | ≥295 MPa |
| Tensile Strength | 490–610 MPa | ≥400 MPa |
| Elongation | ≥21% | ≥22% (Typical) |
| Hardness | Approx. 160–220 HB | Approx. 140–200 HB |
| Weldability | Excellent | Excellent |
| Formability | Good | Excellent |
| Fatigue Resistance | Excellent | Good |
| Load-Bearing Capacity | Higher | Moderate |
Corrosion Resistance of SPA-H and SPA-C Weathering Steel
SPA-H and SPA-C weathering steels contain alloying elements such as copper (Cu), chromium (Cr), and nickel (Ni), which promote the formation of a dense protective patina layer on the steel surface.
This stable layer helps resist moisture, salt spray, and atmospheric corrosion. Both grades provide approximately 4–8 times higher atmospheric corrosion resistance than ordinary carbon steel, reducing maintenance requirements and extending service life by around 2–3 times in typical outdoor and marine environments.
SPA-H and SPA-C Weathering Steel Supplier
GNEE supplies JIS G3125 SPA-H and SPA-C weathering steel plates and coils, strictly complying with JIS standards and providing original mill test certificates (MTC) according to customer requirements.
Product Forms: Available in weathering steel plates, sheets, and coils for shipping containers, railway vehicles, bridges, and outdoor structural applications.
Dimensions: Thickness, width, and length can be customized according to project requirements. Standard sizes and cut-to-length services are available.
Surface Conditions: Available in hot rolled, pickled, shot blasted, and customized surface finishes to meet different fabrication requirements
Processing Services: GNEE provides cutting, drilling, bending, welding preparation, and other customized processing services to improve fabrication efficiency.
Quality Certification: Mill Test Certificate (MTC) and EN 10204 3.1/3.2 inspection certificates are available upon request.
Inspection Services: Laboratory testing includes chemical composition analysis, mechanical property testing (tensile strength, yield strength, elongation), thickness inspection, dimensional inspection, surface inspection, and ultrasonic testing (UT) when required.
GNEE offers high-quality weathering steel plates and coils with reliable performance, flexible sizes, and professional processing services. Contact us for your project solution.
