ASTM A588 Grade B Weathering Steel
ASTM A588 Grade B Weathering Steel - Composition, Properties & Global Equivalents
Comprehensive material data for ASTM A588 Grade B weather resistant steel plate, including chemical composition, mechanical and physical properties, international equivalents, and application guidelines.
Welding, cutting (plasma, oxy-fuel), cold forming, hot forming, machining
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ASTM A588 Grade B Weathering Steel Introduction
ASTM A588 Grade B (A588GRB) is a high-strength, low-alloy structural steel with enhanced atmospheric corrosion resistance. It is widely used in welded bridges, buildings, and structures where weight savings and durability are critical. The material develops a stable, protective oxide layer (patina) when exposed to weather, eliminating the need for painting.
- Excellent weldability and formability
- Superior corrosion resistance compared to carbon steel
- Minimum yield strength of 345 MPa (50 ksi) up to 100 mm thickness
- Supplied as plate, sheet, and structural shapes
ASTM A588 Grade B Weathering Steel Chemical Composition
The following chemical requirements are based on ASTM A588/A588M for Grade B. All values are maximum unless a range is given. The weathering resistance is primarily achieved through additions of chromium, copper, and nickel, which promote the formation of a dense, adherent oxide layer.
| Element | Content (%) | Notes |
|---|---|---|
| Carbon (C) | 0.20 | Max |
| Manganese (Mn) | 0.75 – 1.35 | Range |
| Phosphorus (P) | 0.030 | Max |
| Sulfur (S) | 0.030 | Max |
| Silicon (Si) | 0.15 – 0.50 | Range |
| Nickel (Ni) | 0.50 | Max |
| Chromium (Cr) | 0.40 – 0.70 | Range |
| Copper (Cu) | 0.20 – 0.40 | Range |
| Vanadium (V) | 0.01 – 0.10 | Range |
ASTM A588 Grade B Weathering Steel Thermal & Electrical Physical Properties
The physical properties below are typical for weathering steel grades similar to ASTM A588 Grade B at room temperature and ambient conditions. Values are approximate and may vary slightly with processing and temperature.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic Modulus (E) | 200 | GPa | At 20 °C |
| Shear Modulus (G) | 80 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.30 | — | At 20 °C |
| Thermal Expansion Coefficient (α) | 12.1 | µm/(m·°C) | 0 – 100 °C |
| Thermal Conductivity (λ) | 40 | W/(m·K) | At 20 °C |
| Specific Heat Capacity (cp) | 500 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρe) | 0.22 | µΩ·m | At 20 °C |
ASTM A588 Grade B Weathering Steel Mechanical Properties
Tensile and bend test requirements according to ASTM A588/A588M for Grade B. All properties are in the as-delivered condition. The values vary with product thickness; multiple rows are provided for key thickness ranges.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 345 | MPa | Thickness ≤ 100 mm (4 in.) |
| Yield Strength (ReH) | ≥ 315 | MPa | Thickness > 100 mm to 125 mm (5 in.) |
| Tensile Strength (Rm) | ≥ 485 | MPa | Thickness ≤ 100 mm |
| Elongation in 200 mm (8 in.) | ≥ 18 | % | Thickness ≤ 100 mm |
| Elongation in 50 mm (2 in.) | ≥ 21 | % | Thickness ≤ 100 mm |
| Bend Test (180°) | D = 2.5t | — | t = specimen thickness, for plates ≤ 25 mm |
ASTM A588 Grade B Weathering Steel Fully Equivalent Material Standards & Alternative Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5 | S355J2W+N (1.8965) | Close equivalent; similar weathering properties |
| Japan | JIS G 3114 | SMA490BW | Direct equivalent for welded structures |
| China | GB/T 4171 | Q355NH | Comparable weathering steel for structural use |
| India | IS 11587 | Fe 490 W C | Weathering grade with matching strength level |
| International | ISO 4952 | Fe 510 D W | Similar atmospheric corrosion resistant steel |
ASTM A588 Grade B Weathering Steel Application Introduction
ASTM A588 Grade B is ideal for unpainted applications where the protective patina can form freely. It is extensively used in structural and architectural projects that demand long-term corrosion resistance without maintenance. Proper detailing to allow drainage and avoid crevices is essential for optimal performance.
- Suitable for all conventional welding methods (SMAW, SAW, GMAW) using matching weathering electrode
- Can be punched, sheared, and machined with standard tools
- Not recommended for submerged or continuously wet conditions without protective coating
Product Applications: Weathering steel plates and sheets, Structural sections (H-beams, I-beams, channels, angles), Welded box girders and plate girders, Corrugated roofing and siding panels, Tubular poles and masts
Processed into products: Bridge main girders and cross-beams, Facade cladding and architectural screens, Transmission tower legs and arms, Railcar frames and body panels, Wind turbine tower sections, Storage tank shells
Application industries: Bridge construction (highway, railway, pedestrian), Building and civil engineering (facades, frames, canopies), Electrical transmission and telecommunication towers, Rolling stock and container manufacturing, Sculpture and public art, Shipbuilding (deck components above waterline)
ASTM A588 Grade B Weathering Steel Similar or Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A588 | Grade A | Slightly different chemistry; same strength class |
| United States | ASTM A242 | Type 1 | Earlier weathering steel; similar corrosion resistance |
| United States | ASTM A709 | Grade 50W | Bridge steel with equivalent properties |
| Europe | EN 10025-5 | S355K2W | Higher toughness option for low-temperature use |
| Proprietary | — | Corten B | Trade name historically linked to A588 Grade B |
Notes:
Special considerations: When welding A588 Grade B, low-hydrogen electrodes or filler metals must be used to match the corrosion resistance of the base metal. For cold forming, a minimum bend radius of 2.5t is typically recommended. The material may be ordered with supplementary requirements for Charpy V-notch impact testing (e.g., ASTM A673/A673M).
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