Explore ASTM A588 Grade C Weathering Steel
Explore ASTM A588 Grade C Weathering Steel: Composition, Properties & Equivalents
Comprehensive data on ASTM A588/A588M Grade C carbon and low-alloy high-strength steel coil, including chemical composition, mechanical and thermal properties, equivalent grades, and application guide.
Hot rolling, cold forming, welding, cutting, machining, drilling
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Explore ASTM A588 Grade C Weathering Steel Introduction
ASTM A588/A588M Grade C is a high-strength, low-alloy structural steel with enhanced atmospheric corrosion resistance, commonly referred to as a weathering steel. Its corrosion resistance is achieved through the addition of alloying elements such as copper, chromium, and nickel, which form a dense, adherent oxide patina upon exposure to the atmosphere, eliminating the need for painting in many environments.
- Offers minimum yield strength of 345 MPa (50 ksi) and tensile strength of 485 MPa (70 ksi), making it suitable for load-bearing structures.
- Provides excellent weldability and cold-forming characteristics, similar to conventional carbon steels.
- Widely used in unpainted applications like bridges, building frames, transmission towers, and railcars, where long-term durability and reduced maintenance are critical.
- Delivered in as-rolled, normalized, or controlled-rolled condition, typically available as coils, plates, and structural shapes.
The steel is specified under ASTM A588/A588M standard and is often compared internationally to grades like EN S355J2W and JIS SMA490AW.
Explore ASTM A588 Grade C Weathering Steel Chemical Composition
The chemical composition of ASTM A588 Grade C is carefully balanced to provide high strength and atmospheric corrosion resistance. Copper, chromium, and nickel are key alloying elements that promote the formation of a protective patina. Vanadium is added for grain refinement and precipitation strengthening. Maximum limits apply to phosphorus and sulfur for improved ductility and weldability.
| Chemical Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | 0.15 max | Maximum |
| Manganese (Mn) | 0.80 - 1.35 | Range |
| Phosphorus (P) | 0.040 max | Maximum |
| Sulfur (S) | 0.050 max | Maximum |
| Silicon (Si) | 0.15 - 0.40 | Range |
| Copper (Cu) | 0.20 - 0.50 | For weather resistance |
| Chromium (Cr) | 0.40 - 0.70 | For weather resistance |
| Nickel (Ni) | 0.40 max | Maximum |
| Vanadium (V) | 0.01 - 0.10 | Minimum 0.01% |
Explore ASTM A588 Grade C Weathering Steel Thermal and Electrical Physical Properties
These physical properties are typical for low-alloy weathering steel at room temperature and may vary slightly with exact composition. Thermal conductivity and expansion are important for design in temperature-varying environments. The magnetic permeability is similar to that of mild steels, and the electrical resistivity is relatively high compared to pure iron.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Elastic Modulus (E) | 200 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.3 | - | 20°C |
| Thermal Expansion (α) | 12.2 | 10⁻⁶/°C | 0-100°C |
| Thermal Conductivity (λ) | 51.9 | W/(m·K) | 20°C |
| Specific Heat Capacity | 486 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρ_e) | 0.20 | µΩ·m | 20°C |
Explore ASTM A588 Grade C Weathering Steel Mechanical Properties
Mechanical properties apply to plates, coils, and shapes in the as-rolled or normalized condition. Tensile testing is performed in transverse or longitudinal direction per ASTM A6/A6M. For plates over 100 mm thickness, property limits may need special agreement. Bending tests are conducted at 180° with specific mandrel diameters based on thickness.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 345 | MPa | Thickness ≤ 100 mm, 0.2% offset |
| Tensile Strength (Rm) | ≥ 485 | MPa | Thickness ≤ 100 mm |
| Elongation (A) (200 mm) | ≥ 18 | % | Thickness ≤ 100 mm, 200 mm gauge |
| Elongation (A) (50 mm) | ≥ 21 | % | Thickness ≤ 100 mm, 50 mm gauge |
| Bend Test | d = 2t | - | Thickness ≤ 20 mm, 180° |
| Bend Test | d = 3t | - | Thickness >20 to 25 mm, 180° |
| Bend Test | d = 4t | - | Thickness >25 to 50 mm, 180° |
Explore ASTM A588 Grade C Weathering Steel Full Equivalent Standards and Grades for Substitution
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5 | S355J2W (1.8965) | +N / +AR; similar weathering steel, 355 MPa yield |
| Japan | JIS G3114 | SMA490AW | Hot-rolled atmospheric corrosion resisting steel, 490 MPa tensile |
| China | GB/T 4171 | Q355NH | Superior atmospheric corrosion resistance, 355 MPa yield |
| International | ISO 4952 | E355W | Weathering structural steel, 355 MPa min yield |
| Australia/New Zealand | AS/NZS 3678 | WR350 | Hot-rolled structural steel, 350 MPa yield |
Explore ASTM A588 Grade C Weathering Steel Application Introduction
Due to its excellent atmospheric corrosion resistance and good strength-to-weight ratio, ASTM A588 Grade C is a preferred material for outdoor, unpainted steel structures. As the patina develops over time, the steel surface becomes a protective barrier, reducing maintenance costs. Proper design must consider drainage and wet/dry cycles for uniform patina formation. It is not recommended for submerged or buried conditions without additional protection.
Product Applications: Weathering steel bridge girders and trusses, Building frames and long-span structures, Transmission towers and telecommunication poles, Railcars, trailers, and shipping containers, Architectural cladding and sculptures
Processed into products: Bolted structural connections and splice plates, Welded beams, columns, and box girders, Corrosion-resistant cladding panels and facades, Gusset plates, stiffeners, and base plates, Railroad coupling devices and truck frames
Application industries: Bridge and highway construction, Building and civil engineering, Rail and transportation equipment, Power transmission and utility, Port and marine structures
Explore ASTM A588 Grade C Weathering Steel Similar or Nearby Grades for Reference
The following materials share comparable strength levels and may fulfill similar structural roles, but they may differ in corrosion resistance or specific alloy content. Not all are direct substitutes for ASTM A588 Grade C.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A242 | Type 1 | Weathering steel, lower yield strength (345 MPa), higher Cu, but older standard |
| United States | ASTM A572 | Grade 50 | High-strength low-alloy, 345 MPa yield, no added atmospheric corrosion resistance |
| Europe | EN 10025-5 | S355J0W | Weathering steel, 0°C impact, similar strength but lower toughness than J2W |
| Germany (withdrawn) | DIN 17100 | StE 355 | Obsolete but still referenced; comparable to A588, not specifically weathering |
| Russia | GOST 19281 | 10KhSND | Low-alloy structural steel with Cu, Cr, Ni, similar strength |
Notes:
Patina Development: The protective rust layer forms after several cycles of wetting and drying. Uniform appearance may take 6 months to 2 years depending on climate. Welding: Use low-hydrogen processes and matching or undermatching filler metals (e.g., E80TX-X) to ensure weld metal toughness. Preheating is generally not required for thicknesses under 50 mm. Painting: Though designed for unpainted use, Grade C can still be painted for aesthetic or extreme environments; proper surface preparation is essential.
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