ASME SA588 Grade K Weather Resistant Steel Plate
ASME SA588 Grade K Weathering Steel – High-Strength, Corrosion-Resistant Structural Plate
Comprehensive material data for ASME SA588 Grade K (SA588GRK) weather-resistant steel plate, including chemical composition, mechanical properties, thermal and electrical physical properties, international equivalents, similar grades, and application guidance.
Hot rolling, controlled rolling, normalizing, welding, cold forming (limited), cutting, machining
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ASME SA588 Grade K Weather Resistant Steel Plate Introduction
ASME SA588 Grade K (SA588GRK) is a high-strength low-alloy structural steel with enhanced atmospheric corrosion resistance, commonly referred to as weathering steel. Under the ASME Boiler and Pressure Vessel Code, it is specified for welded bridges, buildings, and other structures where weight savings and durability are critical. The alloying elements, particularly copper, chromium, and nickel, form a protective patina that significantly slows corrosion rates in outdoor exposure. Key features:
- Minimum yield strength of 345 MPa (50 ksi) for thicknesses up to 100 mm
- Excellent notch toughness and weldability
- Self-protecting oxide layer eliminates the need for painting in many environments
- Cost-effective over the life cycle due to reduced maintenance
ASME SA588 Grade K Weather Resistant Steel Plate Chemical Composition
The chemical composition of SA588 Grade K is balanced to provide high strength and superior atmospheric corrosion resistance. Copper, chromium, and nickel contribute to the formation of a dense, adherent oxide layer. Carbon and manganese are controlled to ensure weldability. Note: Values are maximum unless a range is indicated.
| Element | Standard Value (max unless range) | Remarks |
|---|---|---|
| Carbon (C) | 0.17 | Max |
| Manganese (Mn) | 0.50 - 1.20 | Range |
| Phosphorus (P) | 0.040 | Max |
| Sulfur (S) | 0.050 | Max |
| Silicon (Si) | 0.25 - 0.50 | Range |
| Nickel (Ni) | 0.40 | Max |
| Chromium (Cr) | 0.40 - 0.70 | Range |
| Copper (Cu) | 0.30 - 0.50 | Range |
| Vanadium (V) | 0.02 - 0.10 | Optional, may be present but not required |
| Columbium (Nb) | 0.005 - 0.05 | Optional, may be present for grain refinement |
ASME SA588 Grade K Weather Resistant Steel Plate Thermal and Electrical Physical Properties
Physical properties are typical for this class of weathering steel and can be used for engineering calculations. Values are not specification requirements but are derived from published data for similar low-alloy steels.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | at 20 °C |
| Modulus of Elasticity (E) | 200 | GPa | at 20 °C |
| Shear Modulus (G) | 77 | GPa | at 20 °C (calculated from E and ν) |
| Poisson's Ratio (ν) | 0.30 | — | at 20 °C |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶/K | 20–100 °C |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20–200 °C |
| Thermal Expansion Coefficient (α) | 13.2 | 10⁻⁶/K | 20–300 °C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | at 20 °C |
| Specific Heat Capacity (cₚ) | 460 | J/(kg·K) | at 20 °C |
| Electrical Resistivity (ρ_e) | 0.25 - 0.30 | µΩ·m | at 20 °C |
ASME SA588 Grade K Weather Resistant Steel Plate Mechanical Properties
Tensile properties for SA588 Grade K plate, shape, and bar products are tested according to ASTM A6/A6M. Values vary slightly with thickness. Bend test: The bend diameter is a multiple of the specimen thickness and is used to verify ductility.
| Property | Standard Requirement | Unit | Test Condition / Thickness |
|---|---|---|---|
| Yield Strength (ReH) | 345 min | MPa | Plate ≤ 100 mm (4 in.) |
| Yield Strength (ReH) | 315 min | MPa | Plate > 100 mm to 125 mm (4–5 in.) |
| Tensile Strength (Rm) | 485 min | MPa | All thicknesses |
| Elongation (A) in 200 mm (8 in.) | 18 min | % | Plate ≤ 100 mm |
| Elongation (A) in 50 mm (2 in.) | 21 min | % | Plate ≤ 100 mm |
| Bend Test (Bend Diameter) | 1.5t | mm | t = specimen thickness, 180° bend |
ASME SA588 Grade K Weather Resistant Steel Plate Exact Equivalent Material Standards and Replaceable Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A588/A588M | Grade K | Identical chemical and mechanical requirements as ASME SA588 Grade K. |
| Europe | EN 10025-5 | S355J2W (1.8965) | Equivalent weathering steel with minimum 355 MPa yield. Impact tested at -20°C. Often used as a direct substitute. |
| Europe | EN 10025-5 | S355K2W (1.8967) | Higher impact toughness variant (tested at -20°C) with similar corrosion resistance. |
| Japan | JIS G3114 | SMA570W | High-strength weathering steel for welded structures. Close match in terms of corrosion resistance and strength. |
ASME SA588 Grade K Weather Resistant Steel Plate Application Introduction
SA588 Grade K weathering steel is ideally suited for unpainted applications in moderate to severe atmospheric environments. It develops a dense, adherent oxide patina that protects the base metal from further corrosion. Design considerations:
- Proper detailing to avoid water ponding and crevices is essential for long-term durability.
- Welding consumables matching the base metal's corrosion resistance, such as AWS E7018-W or equivalent, are recommended.
- Suitable for structural components where a 50 ksi (345 MPa) minimum yield strength is adequate.
Product Applications: Welded plate girders, Box girders, Bridge decks and abutments, Structural trusses, Architectural screens and fins, Rolled steel sections (H-beams, channels)
Processed into products: Main bridge beams and cross-frames, Link slabs and expansion joints, Vehicle frames and suspension brackets, Tower legs and bracing members, Container corner castings and side panels, Exposed architectural brackets and connectors
Application industries: Bridge engineering and construction, Civil infrastructure (highway signs, light poles), Architectural metalwork (facades, cladding), Railway vehicle manufacturing (freight wagons, containers), Port and marine structures (selective use above splash zone), Power transmission towers
ASME SA588 Grade K Weather Resistant Steel Plate Similar / Substitute Material Recommendations
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A588/A588M | Grade A | Yield strength 345 MPa max, slightly different chemistry (higher Cr, lower Cu). Widely available. |
| USA | ASTM A588/A588M | Grade B | Yield 345 MPa; chemistry similar to Grade K but with more flexibility in alloy content. |
| China | GB/T 4171 | Q355NHD (Q355NHD) | High-strength weathering steel with 355 MPa yield; atmospheric corrosion resistance comparable to Corten B. |
| China | GB/T 4171 | Q460NHD | Higher strength variant (460 MPa yield). Used for heavier structural applications. |
Notes:
Welding: Preheating and interpass temperature control are generally not required for thicknesses below 40 mm. For thicker sections, a preheat of 100–150 °C is advised. Corrosion performance: The protective patina forms best when the steel undergoes wet-dry cycling; it may be less effective in continuously humid or marine immersion environments. Certification: When ordered to ASME SA588, material is typically supplied with an ASME material test report and may require additional impact testing if specified in the purchase order.
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