ASME SA709/SA709M Grade 50W Weathering Steel Coil
ASME SA709/SA709M Grade 50W Weathering Steel Coil - High-Strength Low-Alloy Data
Comprehensive technical data for ASME SA709 Grade 50W carbon and low-alloy high-strength steel coil, including chemical composition, mechanical properties, thermal and electrical physical properties, international equivalents, and application guidance.
Hot rolling, cold forming, welding, machining, cutting
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ASME SA709/SA709M Grade 50W Weathering Steel Coil Introduction
ASME SA709/SA709M Grade 50W is a high-strength low-alloy structural steel with improved atmospheric corrosion resistance (weathering steel) specified for use in bridges, buildings, and other structures. It is part of the ASME SA709 standard, which is identical to ASTM A709/A709M. The "W" designation indicates enhanced corrosion resistance through alloying with copper, chromium, and vanadium, allowing it to form a protective oxide layer when exposed to the atmosphere, often eliminating the need for painting.
- Minimum yield strength of 50 ksi (345 MPa) for thicknesses up to 4 in. (100 mm).
- Excellent weldability and formability for structural fabrication.
- Available in coil, plate, and shapes, with delivery condition typically as-rolled, normalized, or quenched and tempered as required.
ASME SA709/SA709M Grade 50W Weathering Steel Coil Chemical Composition
Chemical requirements as per ASME SA709/SA709M for Grade 50W. The steel is alloyed with copper, chromium, and vanadium to provide atmospheric corrosion resistance. Note: Values are maximum unless a range is shown. Elements not listed are typically incidental and limited to standard steelmaking residuals.
| Element | Value (max or range) | Remarks |
|---|---|---|
| Carbon (C) | 0.20 | max |
| Manganese (Mn) | 0.75 – 1.35 | range |
| Phosphorus (P) | 0.04 | max |
| Sulfur (S) | 0.05 | max |
| Silicon (Si) | 0.15 – 0.50 | range |
| Copper (Cu) | 0.20 – 0.40 | range |
| Nickel (Ni) | 0.50 | max |
| Chromium (Cr) | 0.40 – 0.70 | range |
| Vanadium (V) | 0.01 – 0.10 | range |
| Nitrogen (N) | 0.015 | max (if applicable) |
ASME SA709/SA709M Grade 50W Weathering Steel Coil Thermal & Electrical Physical Properties
Typical room-temperature physical properties for Grade 50W weathering steel. These values are not part of the standard but are widely accepted for engineering design. Thermal properties vary slightly with temperature. Note: Properties are comparable to other low-alloy steels with similar composition.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | At 20°C |
| Modulus of Elasticity (E) | 200 | GPa | Tension, room temperature |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.3 | Typical for steel | |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶/K | 20–100°C range |
| Thermal Conductivity (λ) | 42 | W/(m·K) | At 20°C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | At 20°C |
| Electrical Resistivity (ρe) | 0.25 | µΩ·m | At 20°C |
ASME SA709/SA709M Grade 50W Weathering Steel Coil Mechanical Properties
Tensile requirements are based on the standard test methods. Values for Grade 50W apply to hot-rolled condition. Note: Elongation is measured on standard specimens; 200 mm (8 in.) gauge for sheet/coil, 50 mm (2 in.) gauge for plates >12.5 mm. Minimum impact energy may be specified by supplementary requirements.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | 345 min | MPa | Thickness ≤ 100 mm |
| Tensile Strength (Rm) | 485 min | MPa | Thickness ≤ 100 mm |
| Elongation (A) in 200 mm | 18 min | % | Thickness ≤ 100 mm, 50 mm wide specimen |
| Elongation (A) in 50 mm | 21 min | % | Plate thickness >12.5 mm |
| Bend Test (bend diameter) | 1.5t | 180° bend, specimen thickness t ≤ 16 mm | |
| Impact Energy (KV) | As specified | J | Optional supplementary requirement (e.g., 27J at -20°C) |
ASME SA709/SA709M Grade 50W Weathering Steel Coil Full Equivalent Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A709/A709M | Grade 50W | Identical to ASME SA709 Grade 50W |
| European Union | EN 10025-5 | S355J2W+N | +N indicates normalized delivery; also S355K2W for lower temperature impact |
| Japan | JIS G3114 | SMA490AW | Hot-rolled atmospheric corrosion resisting steel; yield 365 MPa typ. |
| China | GB/T 4171 | Q355NH | Equivalent weathering steel; yield ≥355 MPa |
| International | ISO 4952 | Fe510DW | Atmospheric corrosion-resistant structural steel (approximate match) |
ASME SA709/SA709M Grade 50W Weathering Steel Coil Application Introduction
ASME SA709 Grade 50W is designed primarily for welded bridges and other structural applications where weight savings, durability, and atmospheric corrosion resistance are required. Its weathering property often allows unpainted use in many environments, reducing maintenance costs. The steel is readily weldable following standard procedures for low-alloy steels, provided appropriate preheat and interpass temperatures are observed for thicker sections.
Product Applications: Rolled bridge beams and girders, Welded plate girders, Highway sign supports, Lighting poles, Prefabricated bridge decks
Processed into products: Bridge main girders and cross-frames, Column and beam sections for multi-story buildings, Railway underframe members, Truss members for long-span roofs, Corrosion-resistant fasteners and embedded plates
Application industries: Bridge construction and rehabilitation, Structural engineering (building frames, towers), Transportation (railway cars, truck frames), Energy (transmission towers, solar panel supports), Architecture (exposed structural elements, facades)
ASME SA709/SA709M Grade 50W Weathering Steel Coil Similar / Analogous Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A588/A588M | Grade B | Similar weathering steel, yield 345 MPa, slightly different composition |
| USA | ASTM A242/A242M | Type 1 | High-strength low-alloy weathering steel, yield 345 MPa |
| European Union | EN 10025-5 | S355J0W | Lower impact energy version of S355J2W, suitable for less demanding toughness |
| Japan | JIS G3114 | SMA490BW | Higher Cr content variant with similar strength |
| China | GB/T 4171 | Q355GNH | Higher phosphorus version for enhanced weathering, yield ≥355 MPa |
Notes:
- Welding: When joining thicker sections (≥25 mm), preheat of 50-100°C may be required to avoid hydrogen cracking. Low-hydrogen welding processes are recommended.
- Weathering characteristics: The protective patina develops best in alternating wet/dry conditions without prolonged contact with standing water or de-icing salts.
- Dual certification: Grade 50W is often dual-certified to both ASME SA709 and ASTM A588 standards.
- Availability: Commonly supplied as hot-rolled coil, plate, and structural shapes; consult mill for size range.
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