JIS G 3125 SPA-H Corten Steel Plate Material
JIS G 3125 SPA-H Corten Steel Plate - High Atmospheric Corrosion Resistance
Comprehensive data on SPA-H Corten steel plate including chemical composition, mechanical properties, physical properties, international equivalents, and application guide.
Hot rolling, welding, cutting (plasma/laser), bending, forming, machining
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JIS G 3125 SPA-H Corten Steel Plate Introduction
JIS G 3125 SPA-H is a hot-rolled atmospheric corrosion resisting steel, commonly known as Corten steel, designed for welded structures that are exposed to outdoor environments. Its unique chemical composition, enriched with copper, chromium, and nickel, promotes the formation of a dense, adherent protective oxide layer (patina) when subjected to wet-dry cycles. This patina acts as a barrier against further corrosion, often eliminating the need for painting. SPA-H offers high mechanical strength with minimum yield strength of 345 MPa and good weldability, making it suitable for bridges, buildings, railway vehicles, and containers. The steel is typically supplied in the as-rolled condition and can be fabricated using standard methods.
JIS G 3125 SPA-H Corten Steel Plate Chemical Composition
The chemical composition of SPA-H is specifically balanced to enhance corrosion resistance. Key alloying elements—copper, chromium, and nickel—work synergistically to develop a stable patina. Phosphorus is intentionally higher than in common structural steels to improve atmospheric corrosion resistance. The table lists the standard requirements per JIS G 3125.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.12 | |
| Silicon (Si) | 0.25 - 0.75 | |
| Manganese (Mn) | 0.20 - 0.50 | |
| Phosphorus (P) | 0.070 - 0.150 | |
| Sulfur (S) | ≤0.040 | |
| Copper (Cu) | 0.25 - 0.60 | |
| Chromium (Cr) | 0.30 - 1.25 | |
| Nickel (Ni) | ≤0.65 |
JIS G 3125 SPA-H Corten Steel Plate Physical Properties
The physical properties are representative for Corten steel grade SPA-H at room temperature unless otherwise noted. Thermal expansion and thermal conductivity are important for design involving temperature changes. These values are not part of JIS G 3125 but are derived from published data on similar weathering steels.
| Property | Value | Unit | Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | Room temperature |
| Elastic Modulus (E) | 205 - 210 | GPa | 20°C |
| Shear Modulus (G) | 79 - 82 | GPa | 20°C (calculated from E and ν) |
| Poisson's Ratio (ν) | 0.27 - 0.30 | 20°C | |
| Thermal Expansion Coefficient (α) | 11.1 | 10⁻⁶/K | 20-100°C |
| 11.7 | 10⁻⁶/K | 20-200°C | |
| 12.4 | 10⁻⁶/K | 20-300°C | |
| Thermal Conductivity (λ) | 36 - 42 | W/(m·K) | at 100°C |
| Specific Heat Capacity (c) | 460 - 490 | J/(kg·K) | 20-100°C |
| Electrical Resistivity (ρe) | 0.22 - 0.28 | 10⁻⁶ Ω·m | Room temperature |
JIS G 3125 SPA-H Corten Steel Plate Mechanical Properties
The mechanical properties are guaranteed for hot-rolled condition and depend on product thickness. Yield strength and tensile strength decrease slightly with increasing thickness, while elongation values vary with gauge length and specimen orientation. The bend test confirms ductility and formability. Impact properties are not mandatory but can be agreed upon.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥345 | MPa | Thickness ≤ 16 mm, hot-rolled, transverse specimen |
| ≥335 | MPa | Thickness > 16 mm ≤ 40 mm | |
| ≥325 | MPa | Thickness > 40 mm | |
| Tensile Strength (Rm) | 480 - 630 | MPa | Thickness ≤ 16 mm |
| 470 - 620 | MPa | Thickness > 16 mm ≤ 40 mm | |
| 450 - 600 | MPa | Thickness > 40 mm | |
| Elongation (A) | ≥22 | % | Thickness ≤ 5 mm, gauge length 200 mm (No. 5 specimen) |
| ≥17 | % | Thickness > 5 mm ≤ 16 mm, gauge length 200 mm | |
| ≥21 | % | Thickness > 16 mm, gauge length 50 mm (No. 4 specimen) | |
| Bend Test | 180°, inside radius = 1.0 x thickness | Thickness ≤ 16 mm (width of test piece: 30 mm) | |
| 180°, inside radius = 1.5 x thickness | Thickness > 16 mm |
JIS G 3125 SPA-H Corten Steel Plate Fully Equivalent Material Standards and Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A588/A588M | Grade A | Also A242 Type 1 (slightly different P content) |
| China | GB/T 4171 | Q355NH (formerly Q355GNH) | Equivalent high atmospheric corrosion resisting structural steel |
| European Union | EN 10025-5 | S355J2W (1.8965) | Hot-rolled structural steel with improved atmospheric corrosion resistance, impact energy at -20°C |
| International | ISO 4952 | Fe355W-1A | Structural steels with improved atmospheric corrosion resistance |
| Japan | JIS G 3125 | SPA-H | Original standard |
JIS G 3125 SPA-H Corten Steel Plate Application Introduction
SPA-H Corten steel is ideal for applications where long-term durability with minimal maintenance is required. Its self-protecting patina eliminates the need for painting in many environments, reducing lifecycle costs. Common applications include bridge structures, rolling stock, and architectural cladding. The steel is easily welded and formed, enabling complex shapes without significant loss of corrosion resistance.
Product Applications: Steel plates for welded bridge girders, Weathering steel panels for building envelopes, Container wall sheets, Railway vehicle bodies, Electric transmission poles
Processed into products: Main bridge girders, Box column sections, Stiffeners and gusset plates, Corten cladding panels, Welded fabrications for outdoor equipment, Formed channels and angles for structural frameworks
Application industries: Civil engineering and infrastructure (bridges, viaducts), Transportation (railway cars, truck trailers, container chassis), Architecture (facades, roofing, sculptures), Energy (transmission towers, wind turbine towers, chimney stacks), Industrial equipment (ducts, hoppers, silos)
JIS G 3125 SPA-H Corten Steel Plate Closely Related / Similar Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G 3125 | SPA-C | Cold-rolled version of SPA-H, typically thinner gauges, similar composition |
| United States | ASTM A588/A588M | Grade B | Slightly higher manganese, other properties comparable |
| United States | ASTM A606 | Type 4 | High-strength low-alloy atmospheric corrosion resistant steel, thinner sheet/coil |
| European Union | EN 10025-5 | S355J0WP | Higher phosphorus content variant, suitable for less demanding impact conditions |
| China | GB/T 4171 | Q355GNH | Same strength level, slightly different chemistry |
Notes:
The atmospheric corrosion resistance of SPA-H develops over time under alternating wet-dry conditions; in continuously wet environments, the patina may not form properly. It is not recommended for use in submerged or buried applications without additional protection. The steel is magnetic and exhibits typical ferritic-pearlitic microstructure. For welding, low-hydrogen processes and matching weathering steel consumables are advocated to maintain corrosion resistance. Detailed guidance can be found in JIS G 3125 and supplier datasheets.
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