ASME SA709 Grade 50W Weathering Steel Plate
ASME SA709 Grade 50W (SA709GR50W) Weathering Steel Plate: High-Strength & Corrosion-Resistant
Comprehensive material properties and equivalents for ASME SA709 Grade 50W (SA709GR50W) high-strength low-alloy structural steel plate with enhanced atmospheric corrosion resistance.
Hot rolling, controlled rolling, normalizing, welding, cutting, forming, machining
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ASME SA709 Grade 50W Weathering Steel Plate Introduction
ASME SA709 Grade 50W (SA709GR50W) is a high-strength, low-alloy structural steel plate with improved atmospheric corrosion resistance, commonly referred to as weathering steel. Specified by the ASME Boiler and Pressure Vessel Code, it corresponds technically to ASTM A709 Grade 50W. The alloying elements copper, chromium, and nickel promote the formation of a protective patina that greatly reduces the need for painting in many environments.
- Minimum yield strength of 50 ksi (345 MPa)
- Excellent weldability and formability
- Suitable for bridges, buildings, and other welded structures
- Available in as-rolled, normalized, or controlled-rolled conditions
ASME SA709 Grade 50W Weathering Steel Plate Chemical Composition
The chemical composition conforms to ASME SA709/SA709M Grade 50W. The addition of copper, chromium, and nickel provides enhanced resistance to atmospheric corrosion. All values are maximum unless a range is specified.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | 0.20 max | Typical for weldable structural steel |
| Manganese (Mn) | 0.75 – 1.35 | Enhances strength and toughness |
| Phosphorus (P) | 0.04 max | Residual element |
| Sulfur (S) | 0.05 max | Residual element |
| Silicon (Si) | 0.15 – 0.40 | Deoxidizer and strength contributor |
| Nickel (Ni) | 0.50 max | Improves corrosion resistance |
| Chromium (Cr) | 0.40 – 0.70 | Provides atmospheric corrosion resistance |
| Copper (Cu) | 0.20 – 0.60 | Key element for patina formation |
| Vanadium (V) | 0.01 – 0.10 | Micro-alloying for strength |
| Columbium (Nb) | not specified | May be present as residual or micro-alloy (not required) |
ASME SA709 Grade 50W Weathering Steel Plate Thermal and Electrical Physical Properties
Typical physical properties for low-alloy weathering steel at room temperature. These values are not specified in the standard but are supplied for engineering guidance.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | At 20 °C |
| Modulus of Elasticity (E) | 205 | 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) | 11.7 | 10⁻⁶/K | 20–100 °C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | At 100 °C |
| Specific Heat Capacity (c) | 486 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρₑ) | 0.20 | µΩ·m | At 20 °C |
ASME SA709 Grade 50W Weathering Steel Plate Mechanical Properties
Tensile requirements as per ASME SA709/SA709M for Grade 50W. Elongation values depend on plate thickness and gauge length. These properties are verified in the delivery condition.
| Property | Minimum Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | 345 | MPa | All thicknesses (50 ksi min) |
| Tensile Strength (Rm) | 485 | MPa | All thicknesses (70 ksi min) |
| Elongation (A) – 200 mm (8 in.) | 18 | % | Plates up to 100 mm thick, longitudinal |
| Elongation (A) – 50 mm (2 in.) | 21 | % | Plates ≤ 19 mm (3/4 in.) thick |
| Elongation (A) – 50 mm (2 in.) | 18 | % | Plates 19–38 mm (3/4–1.5 in.) thick |
ASME SA709 Grade 50W Weathering Steel Plate Exact Equivalent Standards and Substitute Grades
The following table lists standards and grades that are technically identical to ASME SA709 Grade 50W. They can be directly interchanged provided the same supplementary requirements are satisfied.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A709/A709M | Grade 50W [345W] | Inch-pound or SI designation, identical to SA709 |
| United States | ASME SA709/SA709M | Grade 50W | Original specification for pressure-retaining structures |
| Canada | CSA G40.21 | 50W | Comparable weathering grade, verify mechanical properties |
ASME SA709 Grade 50W Weathering Steel Plate Application Introduction
ASME SA709 Grade 50W is intended for welded, bolted, or riveted structural applications where enhanced atmospheric corrosion resistance is required. Its ability to develop a stable, protective oxide layer often eliminates the need for painting, reducing maintenance costs.
- Ideal for outdoor structures exposed to alternating wet-dry cycles
- Not recommended for submerged or buried applications without additional corrosion protection
- Forming and welding procedures should follow standard practices for low-alloy steels; preheating may be necessary for thick sections
- Available in plates up to 100 mm thick (depending on the mill)
Product Applications: Bridge girders, beams, and deck plates, Building frames, columns, and trusses, Welded structural assemblies, Railway wagons, bogies, and containers, Transmission tower components, Offshore structural components (above splash zone)
Processed into products: Welded beams and box girders for bridges, Bolted connections and gusset plates, Built-up structural sections, Stiffeners, diaphragms, and bracing, Architectural exposed steel elements, Wind bracing and lateral load resisting components
Application industries: Civil engineering and infrastructure, Bridge construction and maintenance, Architectural and building construction, Railway rolling stock and infrastructure, Transmission towers and utility structures, Shipbuilding and port facilities
ASME SA709 Grade 50W Weathering Steel Plate Similar and Substitute Materials
These grades offer comparable strength and atmospheric corrosion resistance. They may have slightly different composition ranges or supplementary requirements; direct substitution should be confirmed by engineering review.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10025-5 | S355J2W+N (1.8965) | Structural weathering steel with min 355 MPa yield; similar corrosion resistance |
| European Union | EN 10025-5 | S355K2W (1.8967) | Higher toughness variant of S355W |
| Japan | JIS G 3114 | SMA490AW | Weathering steel with min 365 MPa tensile strength; check yield |
| Japan | JIS G 3114 | SMA490BW | Toughness-enhanced version of SMA490AW |
| United States | ASTM A588/A588M | Grade B | High-strength low-alloy weathering steel, similar composition and performance |
Notes:
ASTM A6/A6M General Requirements: Unless otherwise specified, plates are supplied to ASTM A6/A6M tolerances on dimensions, shape, and mass.
Supplementary Requirements: Optional requirements such as impact testing (e.g., S5, S30), tighter chemistry, ultrasonic examination, or improved flatness may be specified at the time of order.
Welding: Low-hydrogen processes are recommended to avoid cold cracking; preheat and interpass temperature control should follow AWS D1.1 or equivalent.
Availability: Common thicknesses range from 6 mm to 100 mm; widths up to 3 m and lengths up to 12 m are typical.
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