ASTM A588 Grade C (A588GRC) Weathering Steel Plate
ASTM A588 Grade C Weathering Steel Plate – High-Strength, Corrosion-Resistant Structural Material
Explore ASTM A588 Grade C (A588GRC) weather resistant steel plate: chemical composition, mechanical properties, thermal and electrical physical data, equivalent grades, and main applications in bridges, building facades, and structural components.
Cutting, welding, bending, punching, machining, hot forming, cold forming
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ASTM A588 Grade C Weathering Steel Plate Introduction
ASTM A588 Grade C is a high-strength, low-alloy structural steel with enhanced atmospheric corrosion resistance, often referred to as weathering steel. Its chemical composition includes elements such as copper, chromium, nickel, and vanadium, which form a dense, self-protecting oxide layer when exposed to alternating wet and dry cycles. This patina eliminates the need for painting in many environments, significantly reducing maintenance costs. The grade delivers a minimum yield strength of 345 MPa (50 ksi) and tensile strength of 485 MPa (70 ksi) for plates up to 100 mm thick, combined with good weldability and toughness. Key features:
- Superior corrosion resistance in unpainted applications
- Cost-effective due to low lifecycle maintenance
- Weldable with standard procedures
- Available in a range of plate thicknesses and shapes
A588 Grade C is commonly supplied in the as-rolled, normalized, or quenched and tempered condition, and finds extensive use in bridges, building structures, transmission towers, and architectural cladding.
ASTM A588 Grade C Weathering Steel Plate Chemical Composition
The chemical composition of ASTM A588 Grade C is designed to promote the formation of a protective patina while maintaining structural strength. Carbon and manganese provide base strength; copper, chromium, nickel, and vanadium work synergistically to enhance atmospheric corrosion resistance. Phosphorus and sulfur are restricted to ensure weldability and toughness. Actual values are reported per heat analysis and must conform to the limits below per ASTM A588/A588M.
- Elements not listed but required by the standard may be present for grain refinement or deoxidation.
- Silicon and vanadium contribute to strength and fine-grained structure.
| Element | Standard Value (max unless range given) | Remarks |
|---|---|---|
| Carbon (C) | 0.15% | |
| Manganese (Mn) | 0.80–1.35% | |
| Phosphorus (P) | 0.04% | |
| Sulfur (S) | 0.05% | |
| Silicon (Si) | 0.15–0.40% | |
| Nickel (Ni) | 0.25–0.50% | |
| Chromium (Cr) | 0.30–0.50% | |
| Copper (Cu) | 0.20–0.50% | |
| Vanadium (V) | 0.01–0.10% | |
| Iron (Fe) | Balance | Approximately 97–98% |
ASTM A588 Grade C Weathering Steel Plate Thermal and Electrical Physical Properties
The following physical properties are typical for ASTM A588 Grade C at room temperature unless otherwise noted, and are derived from published data for weathering steels of similar composition. These values are not mandatory in the standard but are useful for design calculations involving thermal expansion, load deflection, and heat transfer.
- Density may vary slightly with actual chemical composition.
- Thermal and electrical values are influenced by temperature and processing history.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | Ambient temperature |
| Modulus of Elasticity (E) | 200 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Room temperature |
| Poisson's Ratio (ν) | 0.3 | – | Room temperature |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 0–100°C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | Room temperature |
| Specific Heat Capacity | 480 | J/(kg·K) | Room temperature |
| Electrical Resistivity (ρₑ) | 0.20 | μΩ·m | Room temperature |
ASTM A588 Grade C Weathering Steel Plate Mechanical Properties
Mechanical properties are determined from standard transverse test specimens per ASTM A6/A6M. Values shown apply to plates up to 100 mm thick in the as-rolled or normalized condition. For thicker sections or different product forms, consult ASTM A588/A588M.Charpy V‑notch impact energy may be specified by supplementary requirements (e.g., S5) for structural applications requiring low‑temperature toughness.
- Tensile properties are valid at room temperature.
- Bend test requirements are typically 180° flat bend for ductility verification.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) min | 345 | MPa | Plate thickness ≤100 mm |
| Tensile Strength (Rm) min | 485 | MPa | Plate thickness ≤100 mm |
| Elongation in 200 mm (A) min | 18 | % | Plate thickness ≤100 mm |
| Elongation in 50 mm (A) min | 21 | % | Plate thickness ≤100 mm |
| Bend Test | 180° flat bend, no cracks | – | Mandrel diameter = specimen thickness |
ASTM A588 Grade C Weathering Steel Plate Fully Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| – | – | – | No direct international standard exactly duplicates the chemistry and property combination of ASTM A588 Grade C. However, the grades listed below are used interchangeably in many applications after engineering assessment. |
ASTM A588 Grade C Weathering Steel Plate Application Introduction
ASTM A588 Grade C is engineered for structural applications where long-term, low-maintenance corrosion resistance is required. Its self-protecting oxide layer makes it suitable for both exposed and sheltered locations, provided proper design details are followed to avoid water and debris entrapment.
- Avoid contact with de‑icing salts and corrosive chemicals unless additional protection is applied.
- Painting is optional; when required, surface preparation must remove the existing patina.
Product Applications: Welded bridge girders and box sections, Weathering steel plate bridge decks, Atmospheric-exposed structural columns and beams, Sculptures and decorative panels, Pole structures and lighting masts, Rolled shapes and merchant bars
Processed into products: Bridge bearing stiffeners and diaphragms, Crane beams and runway structures, Container corner castings and side panels, Tower legs and cross arms, Building entrance beams and canopy frames, Elevator guide rail brackets (exposed)
Application industries: Bridge and highway construction, Architectural and building facades, Railway vehicle manufacturing, Transmission and telecommunication towers, Shipping containers and port equipment, Mining and heavy industrial plants
ASTM A588 Grade C Weathering Steel Plate Similar/Alternative Weathering Steel Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A588/A588M | Grade A, Grade B, Grade K | Different Cu/Ni/Cr balances; Grade B is most common; Grade K has higher Mn. |
| USA | ASTM A242/A242M | Type 1 | Lower yield strength (min 345 MPa) but similar corrosion resistance; often used for lighter sections. |
| Europe | EN 10025-5 | S355J2W, S355J0W, S355K2W | Comparable strength (355 MPa yield); chemistry differs (e.g., higher Cr, Cu). Impact test options available. |
| Japan | JIS G 3114 | SMA570W | Higher tensile strength (570 MPa class); corrosion resistance via Cu-Cr-Ni, but different min yield. |
| Australia/NZ | AS/NZS 3678 | WR350 | Weathering steel with 350 MPa yield; chemistry may vary; consult supplier for full correspondence. |
Notes:
ASTM A588 Grade C is generally supplied with a mill test report showing chemical analysis and mechanical test results. Supplementary requirements for notch toughness (e.g., Charpy V‑notch at 0°C, ‑20°C, or ‑46°C) can be added per ASTM A6/A6M. For welded structures, preheat and interpass temperature control may be necessary depending on plate thickness and diffusible hydrogen levels; consumables matching the base metal strength and corrosion resistance are recommended. Surface condition may include mill scale and a light rust bloom, which does not affect subsequent performance.
For applications requiring tight flatness or unmachined surfaces, plates can be ordered in the as‑rolled condition with optional flattening or leveling. When ordering, specify ASTM A588 Grade C, optionally with supplementary requirements (e.g., S2, S5) and any additional testing such as ultrasonic examination.
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