ASTM Weathering Steel Specifications
Weathering steels encompass a range of ASTM specifications and trademarked products known for their corrosion-resistant properties. These specifications include:
The most notable trademarked product within this family is Cor-ten®.
Understanding Weathering Steels
Weathering steels, such as those covered by ASTM specifications, are designed to develop a stable rust-like appearance over time. This natural patina acts as a protective layer, enhancing the steel’s durability and eliminating the need for painting.
These specifications are widely used in various applications, including architectural structures, outdoor sculptures, bridges, and shipping containers, where resistance to atmospheric corrosion is crucial.
Cor-Ten® Steel Specifications
Cor-Ten® is a trademarked name by United States Steel Corporation (USS) for an atmospheric corrosion-resistant steel. It was developed to provide higher strength and an extended lifecycle in applications where durability is essential.
Key Features:
- Natural Patina Formation: Cor-Ten® steel naturally develops a layer of rust or patina when exposed to various atmospheric conditions. This patina acts as a protective barrier, guarding the material against further corrosion.
Equivalent ASTM Corten Steel Specifications
As Cor-Ten® gained popularity, other steel mills began producing their versions of atmospheric corrosion-resistant steel. ASTM created equivalent specifications to Cor-Ten® steel, suitable for most applications. These include:
- ASTM A588
- ASTM A242
- ASTM A606-4
- ASTM A847
- ASTM A709-50W
ASTM A588 Steel Specification
ASTM A588 is a high-strength, low-alloy structural steel specification designed for structural steel shapes like angles, channels, beams, steel plates, and bars. It offers improved atmospheric corrosion resistance, making it suitable for applications where weight savings, durability, and extended lifecycle are important factors.
Key Features:
- A588 provides significantly better atmospheric corrosion resistance compared to carbon steels such as A36 and A572-50, with or without copper addition. This makes it suitable for many applications even in unpainted conditions.
- ASTM A588 has a minimum yield strength of 50 ksi (kilo-pounds per square inch) and a minimum tensile strength of 70 ksi. This high strength ensures structural integrity and load-bearing capability in various environments.
Applications:
ASTM A588 is primarily used in welded bridges and other structures where its corrosion-resistant properties contribute to longer lifecycles and reduced maintenance needs.
ASTM A242 Steel Specification
ASTM A242 is a high-strength, low-alloy structural steel specification known for its improved atmospheric corrosion resistance. It is typically used for steel plates up to one-half inch in thickness.
Key Features:
- A242 offers significantly better atmospheric corrosion resistance compared to carbon steels like A36 and A572-50, with or without copper addition. This makes it suitable for many applications even without painting.
- ASTM A242 has a minimum yield strength of 50 ksi (kilo-pounds per square inch) and a minimum tensile strength of 70 ksi. This high strength ensures durability and structural integrity in various environmental conditions.
Applications:
ASTM A242 is commonly used in structural applications where resistance to atmospheric corrosion is crucial. It is suitable for structures exposed to harsh weather conditions, offering extended lifecycle benefits and reduced maintenance requirements.
ASTM A606-4 Steel Specification
ASTM A606-4 is a high-strength, low-alloy specification designed for hot and cold rolled steel sheet, strip, and coil. It is intended for structural and miscellaneous purposes where weight savings and enhanced durability are critical factors.
Key Features:
- A606-4 offers superior atmospheric corrosion resistance compared to carbon steels, with or without copper addition. This makes it suitable for many applications without requiring paint.
- A606-4 contains additional alloying elements that contribute to its enhanced corrosion resistance and mechanical properties.
- ASTM A606-4 has a minimum yield strength of 50 ksi (kilo-pounds per square inch) and a minimum tensile strength of 70 ksi. This high strength ensures structural integrity and load-bearing capability in various environments.
Applications:
ASTM A606-4 is commonly used in structural applications where resistance to atmospheric corrosion is crucial. It is suitable for outdoor structures and architectural elements that require durability and aesthetic appeal without the need for painting.
ASTM A847 Steel Specification
ASTM A847 is a high-strength, low-alloy steel specification that covers cold-formed welded square and rectangular tubing and pipe. It is designed for structural applications where high strength and enhanced corrosion resistance are essential.
Key Features:
- A847 provides significantly better atmospheric corrosion resistance compared to carbon steel, with or without copper addition. This makes it suitable for various environments without needing paint.
- ASTM A847 is intended for welded, bolted, or riveted construction of bridges and other structures. Its high strength ensures durability and reliability in demanding applications.
- A847 has a minimum yield strength of 50 ksi (kilo-pounds per square inch) and a minimum tensile strength of 70 ksi. This ensures robust structural performance under load.
Applications:
ASTM A847 is commonly used in the construction of bridges and other structures where both strength and corrosion resistance are critical. It can be used in bare (unpainted) conditions, offering cost savings and maintenance benefits.
ASTM A709-50W Steel Specification
ASTM A709-50W is a standard specification for structural steel used primarily in bridges. It covers high-strength, low-alloy steel structural shapes, plates, and bars.
Key Features:
- A709-50W offers significantly better atmospheric corrosion resistance compared to carbon steel, with or without copper addition. This makes it suitable for various environments without the need for painting.
- ASTM A709-50W specifies an atmospheric corrosion index of 6.00 or higher, indicating its superior resistance to corrosion in most atmospheric conditions.
- Designed for structural use in bridges and other structures, A709-50W is suitable for applications where high strength and corrosion resistance are essential. It can be used in bare (unpainted) conditions, reducing maintenance costs and enhancing durability.
ASTM A871-65 Steel Specification
ASTM A871-65 is a high-strength, low-alloy structural steel plate designed for applications requiring improved atmospheric corrosion resistance.
Key Features:
- A871-65 offers substantially better atmospheric corrosion resistance compared to carbon steels, with or without copper addition. This property allows it to be used in various environments without requiring paint.
- A871-65 specification provides for a minimum yield strength of 65 ksi (kilo-pounds per square inch) and a minimum tensile strength of 80 ksi. These high strengths ensure structural integrity and reliability under load.
- A871-65 is primarily used for transmission and lighting poles, serving as an aesthetically pleasing alternative to galvanized structures. Its corrosion-resistant properties make it suitable for outdoor applications where durability and visual appeal are important.
ASTM A572-65 Steel Specification
ASTM A572-65 is a high-strength, low-alloy columbium-vanadium structural steel. It is known for its excellent strength properties, making it suitable for structural applications requiring high strength and durability.
Key Features:
- A572-65 has a minimum yield strength of 65 ksi (kilo-pounds per square inch) and a minimum tensile strength of 80 ksi. These properties ensure robust structural performance in various applications.
- It is purchased with a limited maximum silicon content of 0.05% to facilitate the subsequent galvanizing process. This makes it suitable for galvanized transmission and lighting poles.
- A572-65 is supplied to meet a Charpy V-Notch impact test requirement of 15 ft-lb at -20°F, ensuring its suitability for cold weather conditions.
Applications:
The primary application of ASTM A572-65 is in galvanized transmission and lighting poles, where its high strength and low silicon content facilitate the galvanizing process while maintaining structural integrity.
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