ASME SA588/SA588M Grade C Weathering Steel Coil
ASME SA588/SA588M Grade C Weathering Steel Coil: Properties, Equivalents & Applications
Complete technical data sheet for ASME SA588/SA588M Grade C carbon and low-alloy high-strength steel coil, including chemical composition, mechanical and physical properties, international equivalents, and detailed application guidance.
Hot rolling, controlled rolling, normalizing, thermo-mechanical controlled processing (TMCP), welding, cold forming
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ASME SA588/SA588M Grade C Weathering Steel Coil Introduction
ASME SA588/SA588M Grade C is a high-strength low-alloy structural steel with improved atmospheric corrosion resistance, often referred to as a weathering steel. By adding small amounts of copper, chromium, nickel, and vanadium, it forms a dense, adherent protective oxide layer when exposed to outdoor environments, significantly reducing the need for painting and maintenance. It provides a minimum yield strength of 345 MPa (50 ksi) and tensile strength of 485 MPa (70 ksi), making it suitable for welded bridges, buildings, and other structures where weight savings and durability are critical. Typical supply forms include hot-rolled coils, plates, strips, and structural shapes.
ASME SA588/SA588M Grade C Weathering Steel Coil Chemical Composition
The chemical requirements are specified in ASME SA588/SA588M Table 1. Grade C is designed to provide enhanced atmospheric corrosion resistance through a balanced addition of copper, chromium, and nickel, while keeping carbon low for good weldability.
| Chemical Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.15 | Ladle analysis |
| Manganese (Mn) | 0.80 - 1.35 | Ladle analysis |
| Phosphorus (P) | ≤0.04 | Ladle analysis |
| Sulfur (S) | ≤0.05 | Ladle analysis |
| Silicon (Si) | 0.15 - 0.40 | Ladle analysis |
| Nickel (Ni) | ≤0.30 | Ladle analysis |
| Chromium (Cr) | 0.30 - 0.50 | Ladle analysis |
| Copper (Cu) | 0.20 - 0.50 | Ladle analysis |
| Vanadium (V) | 0.01 - 0.10 | Ladle analysis |
ASME SA588/SA588M Grade C Weathering Steel Coil Thermal and Electrical Physical Properties
The following physical properties are typical values for low-alloy weathering steels and may not be part of the mandatory ASME SA588 standard. They are provided for engineering reference and are valid near room temperature unless otherwise indicated.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 205 | GPa | At 20 °C |
| Shear Modulus (G) | ~80 | GPa | Approximate value at 20 °C |
| Poisson's Ratio (ν) | 0.30 | - | At 20 °C |
| Thermal Expansion Coefficient (α) | 12.2 | µm/m·°C | Between 20 °C and 100 °C |
| Thermal Conductivity (λ) | 42.6 | W/m·K | At 20 °C |
| Specific Heat Capacity (cp) | 486 | J/kg·K | At 20 °C |
| Electrical Resistivity (ρe) | ~0.17 | µΩ·m | At 20 °C |
ASME SA588/SA588M Grade C Weathering Steel Coil Mechanical Properties
Mechanical properties are given in ASME SA588/SA588M Table 2 for products in the as-rolled, normalized, or TMCP condition. The values below apply to thicknesses up to 100 mm (4 in.) unless otherwise noted. Elongation requirements depend on the gauge length specified; two standard gauge lengths are commonly used.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥345 | MPa (ksi) | At ambient temperature, for thickness ≤ 100 mm; equivalent to 50 ksi |
| Tensile Strength (Rm) | ≥485 | MPa (ksi) | At ambient temperature, for thickness ≤ 100 mm; equivalent to 70 ksi |
| Elongation (A) in 200 mm (8 in.) | ≥18 | % | At ambient temperature, gauge length 200 mm |
| Elongation (A) in 50 mm (2 in.) | ≥21 | % | At ambient temperature, gauge length 50 mm |
ASME SA588/SA588M Grade C Weathering Steel Coil Completely Equivalent Material Standards and Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASME SA588/SA588M | Grade C | Base standard for pressure vessel and structural applications |
| USA | ASTM A588/A588M | Grade C | Identical chemical and mechanical requirements; the source standard for ASME SA588 |
ASME SA588/SA588M Grade C Weathering Steel Coil Application Introduction
ASME SA588 Grade C steel coil is primarily intended for welded, bolted, or riveted structures where enhanced resistance to atmospheric corrosion can reduce lifecycle costs. It is typically used in the bare (unpainted) condition, developing a stable, protective patina that slows further corrosion. The material is readily weldable and formable using conventional shop practices, provided that suitable low-hydrogen procedures are followed.
Product Applications: Weathering steel bridge girders and decks, Architectural facades and exposed building frames, Transmission line towers and poles, Railway cars, hoppers, and tank shells, Cargo containers and trailer chassis, Guardrails and sign support structures
Processed into products: Box girders and plate girders for bridges, Welded tubular sections and hollow structural sections (HSS), Tower leg angles and lattice tower members, Bent plates and formed panel sections, Welded beams and columns for building frames, Structural stiffeners, gussets, and connection plates
Application industries: Bridge construction and highway infrastructure, Commercial and industrial building structures, Transmission towers and telecommunication masts, Railway rolling stock and freight wagons, Container and transport equipment manufacturing, Mining and heavy equipment structural parts
ASME SA588/SA588M Grade C Weathering Steel Coil Similar/Alternative Weathering Steel Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5 | S355J2W + N / +AR | Similar strength class (355 MPa yield) and weathering characteristics; often used for structural steel work and bridges. |
| Canada | CSA G40.21 | 350W | Comparable yield strength and weldable weathering steel, commonly used in North American bridges. |
| Japan | JIS G 3114 | SMA490AW / SMA490BW | Weathering steel for welded structures with a minimum yield strength of 365 MPa; close corrosion resistance. |
| China | GB/T 4171 | Q355NH (or Q345NHL) | Chinese weathering structural steel with similar strength and atmospheric corrosion resistance, often used in building and bridge engineering. |
Notes:
Corrosion behaviour: When fully exposed to alternating wet and dry cycles, SA588 Grade C develops a tightly adherent oxide coating (patina) that significantly reduces further corrosion. It is not recommended for submerged or buried applications without additional protection. Welding guidance: Low-hydrogen welding processes (SMAW, GMAW, SAW) are recommended. Matching weathering electrodes (e.g., AWS E80W or equivalent) should be used to ensure the weld zone exhibits similar corrosion resistance. Preheating may be required depending on thickness and joint restraint. Forming: The material can be cold-formed within the limits of its specification. Hot forming should be carried out within the normalizing or controlled-rolling temperature range, followed by appropriate cooling.
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