ASTM A709 Steel, grade 50 and 50W

ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm Product Information -:- For detailed product information, please contact sales. -: ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm Synonyms -:- For detailed product information, please contact sales. -:

ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm Product Information -:- For detailed product information, please contact sales. -: ## **Product Specification: ASTM A709 High-Performance Structural Steel (Grades 50 & 50W)** ### **Product Designation** * **Standard:** ASTM A709 / A709M * **Grades Covered:** **Grade 50 (A709-50)** & **Grade 50W (A709-50W)** * **Condition:** As-rolled, thermo-mechanically controlled processed (TMCP), or quenched & tempered (depending on thickness/product form). * **Product Form:** Shapes, plates, and bars. * **Thickness/Size Scope:** **≤ 100 mm (4 inches)** – For plates, this is typically the as-rolled or TMCP condition. ### **Overview** ASTM A709 is the comprehensive standard specification for **carbon and high-strength low-alloy (HSLA) structural steel shapes, plates, and bars** for use in **bridges and other structural applications**. It consolidates several traditional ASTM specs (like A36, A572, A588) into a single bridge-focused standard with additional toughness requirements. * **Grade 50:** The most common high-strength steel for bridges, offering a minimum yield strength of 50 ksi (345 MPa). * **Grade 50W:** The "W" denotes "Weathering." This grade is chemically designed to form a stable, adherent rust patina (oxide layer) when exposed to the atmosphere, which inhibits further corrosion. This eliminates the need for protective painting in many environments, offering significant lifecycle cost savings. ### **1. Chemical Composition (Maximum % by Weight, for Plates ≤ 100mm)** Composition varies by production process (as-rolled vs. TMCP) and grade. The following are typical maximums or ranges. | Element | Grade 50 (Typical) | Grade 50W (Typical) | Role & Effect | | :--- | :--- | :--- | :--- | | **Carbon (C)** | 0.23 max | 0.19 max | Provides strength; lower in 50W for improved weldability and toughness. | | **Manganese (Mn)** | 1.35 max | 0.80 - 1.35 | Increases strength and hardenability; crucial for achieving yield strength. | | **Phosphorus (P)** | 0.04 max | 0.04 max | Impurity; controlled low. In 50W, it aids weathering resistance. | | **Sulfur (S)** | 0.05 max | 0.05 max | Impurity; controlled low for improved ductility and through-thickness properties. | | **Silicon (Si)** | 0.40 max | 0.30 - 0.65 | Deoxidizer; in 50W, it is essential for promoting the protective weathering patina. | | **Copper (Cu)** | 0.20 min (if specified) | **0.20 - 0.40** | **Key for 50W.** Critical element for atmospheric corrosion resistance. Often present in Grade 50 as well. | | **Chromium (Cr)** | - | 0.40 - 0.70 | Enhances weathering resistance in Grade 50W. | | **Nickel (Ni)** | - | 0.25 - 0.50 | Enhances weathering resistance and low-temperature toughness in Grade 50W. | | **Vanadium (V)** | 0.01 - 0.15* | 0.02 - 0.10* | Microalloying element; provides grain refinement and precipitation strengthening (common in TMCP grades). | | **Columbium (Cb/Nb)**| 0.005 - 0.05* | 0.005 - 0.05* | Microalloying element; powerful grain refiner and strengthener (common in TMCP grades). | *Note: *Microalloying elements (V, Cb) are used individually or in combination in modern TMCP steels to achieve mechanical properties with lower carbon content, enhancing weldability.* ### **2. Physical & Mechanical Properties (For Material ≤ 100 mm)** **A. Physical Properties (Typical)** * **Density:** 7.85 g/cm³ (0.284 lb/in³) * **Elastic Modulus:** 200 GPa (29,000 ksi) * **Poisson's Ratio:** 0.30 * **Coefficient of Thermal Expansion:** 11.7 x 10⁻⁶ /K (70-200°F) **B. Mechanical Properties (Minimum Required per ASTM A709)** | Property | Grade 50 (345) | Grade 50W (345W) | Test Condition | | :--- | :--- | :--- | :--- | | **Yield Strength (min)** | 345 MPa (50 ksi) | 345 MPa (50 ksi) | At room temperature | | **Tensile Strength** | 450 MPa (65 ksi) min | 485 MPa (70 ksi) min | At room temperature | | **Elongation (in 200 mm)** | 21% min | 21% min | | | **Elongation (in 50 mm)** | 24% min | 24% min | | | **Charpy V-Notch Impact Energy**| **Required** | **Required** | **Key differentiator from A572.** | | **Test Temperature** | Often 21°C (70°F) or 0°C (32°F) | Often -12°C (10°F) or lower | Specified by the buyer based on service location. | | **Minimum Energy** | 27 J (20 ft-lbf) typical | 27 J (20 ft-lbf) typical | For example, at 0°C for Zone 2. | ### **3. Product Applications** These grades are the workhorses of modern structural engineering, particularly in transportation infrastructure. * **Bridge Construction (Primary Application):** * **Grade 50:** Main load-carrying members in painted bridges – girders (I-beams, box girders), floor beams, cross-frames, and diaphragms. * **Grade 50W:** **Unpainted (weathering) bridges.** Used for exposed girders and structures where the aesthetic of the rust-like patina is desired and maintenance access is difficult. Commonly used for highway overpasses, pedestrian bridges, and rural bridges. * **Other Structural Applications:** * Building frames where high strength-to-weight ratio is beneficial. * Support structures for heavy equipment. * Transmission towers and electrical substation structures. * Barges and shipbuilding components. ### **4. International Standards & Designations** ASTM A709 is the dominant specification for bridge steel in North America. Close equivalents exist in other systems, but direct substitution requires careful review of property and testing requirements. | Standard System | Grade 50 Equivalent | Grade 50W Equivalent | Notes | | :--- | :--- | :--- | :--- | | **ASTM (USA)** | **A709-50** | **A709-50W** | The primary specification. | | **AASHTO (USA)** | **M270 Grade 50** | **M270 Grade 50W** | Identical to ASTM A709 for bridge construction; mandated by most US State DOTs. | | **CSA (Canada)** | **G40.21 350W** | **G40.21 350A** (Cor-ten-type) | CSA 350W (yield in MPa) is similar to Grade 50. CSA 350A is a weathering steel. | | **EN (Europe)** | **S355J2/N** | **S355J0W / S355J2W** | EN 10025-2 (S355) and EN 10025-5 (Weathering). S355 has a 355 MPa yield strength. | | **JIS (Japan)** | **SM490YA** | **SMA490AW** | JIS G3106 / G3114. SMA series are weathering steels. | | **ISO** | **ISO 630-2: E355** | **ISO 4952: E355WP** | International standardized equivalents. | ### **Key Features & Selection Guide** * **Toughness:** A709 mandates Charpy V-Notch testing, making it superior to basic structural specs (like A572 Gr. 50) for fracture-critical applications like bridges. * **Weathering Steel (50W):** Use where a permanent, maintenance-free finish is acceptable. Not recommended for consistently wet, salt-laden (coastal/marine), or highly industrial (high SO₂) environments without protection. * **Weldability:** Both grades exhibit excellent weldability due to controlled carbon content and CEV (Carbon Equivalent Value). Grade 50W, with its typically lower carbon, is often easier to weld. * **Availability:** Grade 50 is the most widely available high-strength structural steel. Grade 50W is also commonly stocked in major markets. ### **Summary** **ASTM A709 Grades 50 and 50W (≤ 100 mm)** represent the standard for high-performance, **toughness-guaranteed structural steels** in bridge and construction applications. **Grade 50** provides reliable high strength for painted structures, while **Grade 50W** offers the unique economic and aesthetic advantage of a maintenance-free weathering surface. The inclusion of mandatory impact testing in the A709 standard ensures these materials possess the necessary fracture resistance for the dynamic and safety-critical loads encountered in modern infrastructure, distinguishing them from ordinary structural steels. -:- For detailed product information, please contact sales. -: ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm Specification Dimensions Size： Diameter 20-1000 mm Length <4140 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm -:- For detailed product information, please contact sales. -:

Packing of ASTM A709 Steel, grade 50 and 50W, ≤ 100 mm -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 611 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition