SPA-H and SPA-C steel plates are high-performance weathering steels specified under JIS G 3125, widely recognized for their excellent atmospheric corrosion resistance and stable mechanical properties.
When exposed to air and moisture, both grades form a dense and adherent rust patina that significantly slows further corrosion. This self-protective behavior eliminates or greatly reduces the need for painting and periodic maintenance, making SPA-H and SPA-C ideal materials for long-term outdoor service.
Compared with ordinary carbon steel, SPA-H and SPA-C offer superior resistance to atmospheric corrosion, especially in industrial, urban, and infrastructure environments, helping to lower lifecycle costs and reduce environmental impact associated with coatings and repainting.
Typical Applications
SPA-H and SPA-C steel plates are widely used in projects requiring both structural strength and long-term weather resistance, including:
Container manufacturing: structural panels and frames exposed to outdoor storage and transport environments
- Bridge and infrastructure construction: girders, decks, guard panels, and structural components
- Automotive and railway vehicles: wagon bodies, underframes, and exterior structural parts
- Architectural cladding and façades: wall panels, screens, and decorative exterior elements
- Outdoor storage tanks and industrial equipment: housings, enclosures, and load-bearing structures
Their ability to maintain structural integrity without frequent repainting makes them particularly suitable for projects designed for decades of service life.
Mechanical Properties (Typical)
| Standard | Grade | Thickness (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|---|---|
| JIS G3125 | SPA-H | 3–50 | ≥345 | 470–630 | ≥21 |
| JIS G3125 | SPA-C | 3–50 | ≥295 | 470–590 | ≥23 |
Detailed Mechanical Properties
| Grade | Thickness (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Impact Energy at −20 °C |
|---|---|---|---|---|---|
| SPA-H | ≤16 | ≥355 | 490–630 | ≥20 | ≥27 J |
| SPA-H | ＞16 | ≥345 | 470–630 | ≥20 | ≥27 J |
| SPA-C | ≤16 | ≥275 | 410–560 | ≥22 | ≥27 J |
| SPA-C | ＞16 | ≥265 | 390–560 | ≥22 | ≥27 J |
Chemical Composition (%)
| Grade | C | Si | Mn | P | S | Cu | Ni | Cr | Nb |
|---|---|---|---|---|---|---|---|---|---|
| SPA-H | ≤0.15 | ≤0.30 | ≤1.00 | ≤0.030 | ≤0.030 | 0.25–0.55 | 0.30–0.60 | 0.40–0.70 | ≤0.10 |
| SPA-C | ≤0.20 | ≤0.30 | ≤1.00 | ≤0.035 | ≤0.035 | 0.15–0.40 | 0.10–0.30 | 0.30–0.60 | ≤0.10 |
Key Features of SPA-H / SPA-C Steel Plates
Proven atmospheric corrosion resistance through alloy-based patina formation
Reliable strength and toughness for load-bearing and structural applications
Reduced maintenance costs by eliminating regular painting systems
Good weldability and formability for fabrication and processing
Available in a wide range of thicknesses, widths, and customized sizes
Packaging & Shipment
Packing: Standard seaworthy packaging
Delivery Time: 7–15 working days after order confirmation
Customized Sizes: Available according to project requirements
Ports: Tianjin / Qingdao / Shanghai
Minimum Order Quantity (MOQ): 1 ton
Q1: What is SPA-H Corten steel?
SPA-H is a Japanese standard weathering steel grade specified in JIS G 3125. It contains alloying elements such as copper, chromium, and nickel, which allow it to form a dense protective rust layer on the surface. This patina significantly slows down further corrosion and improves long-term durability in atmospheric environments.
Q2: What are the main advantages of SPA-H weathering steel?
The key advantages of SPA-H steel include excellent atmospheric corrosion resistance, high strength, and low maintenance cost. Unlike ordinary carbon steel, SPA-H does not require frequent painting or coating, which helps reduce lifecycle costs while maintaining a unique natural appearance.
Q3: Where is SPA-H Corten steel commonly used?
SPA-H steel is widely used in bridges, building structures, architectural façades, railway carriages, containers, air preheaters, and economizers. It is especially suitable for outdoor structures exposed to changing weather conditions for long periods.
Q4: Does SPA-H steel need painting or surface treatment?
In most outdoor applications, no additional painting is required. SPA-H naturally forms a stable rust layer after exposure to the atmosphere. However, in highly corrosive environments (such as marine or high-salt areas), additional surface protection may be recommended to extend service life.
Q5: How long does it take for SPA-H steel to form a stable patina?
Under normal atmospheric conditions, SPA-H steel typically forms a stable protective patina within 6 to 24 months
