ASTM A242 Steel – Corten A

ASTM A242 steel is a standard specification for carbon and low-alloy, high-strength structural steel plates. This specification includes high-strength steel profiles, plates, and bars designed for welded, riveted, or bolted constructions.

It is primarily used to reduce weight or enhance the durability of steel constructions, especially in environments where resistance to atmospheric corrosion is important. Known commonly as Corten steel, ASTM A242 develops a protective rust-like appearance when exposed to weather, which helps protect the steel from further corrosion.

Key Properties:

• Corrosion Resistance: ASTM A242 is designed to withstand corrosion in outdoor environments, forming a stable rust layer that protects the underlying steel from further deterioration.
• Mechanical Properties:
  • Yield Strength: Approximately 345 MPa (50,000 psi).
  • Tensile Strength: Ranges from 450 to 620 MPa (65,000 to 90,000 psi).
  • Elongation: Typically around 21% in 200 mm.

Typical Applications:

ASTM A242 steel is widely used in various industries, including:

• Construction: Ideal for structural components in buildings, bridges, and other infrastructure projects where durability and aesthetic appeal are desired.
• Art and Design: Frequently used in sculptures, landscaping, and architectural features due to its unique weathered appearance.
• Transportation: Utilized in the manufacturing of railway cars and shipping containers, where resistance to harsh environmental conditions is crucial.

ASTM A242 steel possesses resistance to atmospheric corrosion

The steel plates produced under the ASTM A242 standard, also known as weathering steel plate, are classified as either semi-killed or fully killed steel. These plates exhibit excellent resistance to atmospheric corrosion, making them suitable for a wide range of working environments.

ASTM A242 weathering steel is substantially better than that of carbon structural steel with or without copper added-in.

Why A242 plates called weathering steel plate

When appropriately exposed to the atmosphere, ASTM A242 steel can develop a natural rust patina that protects the steel from further exposure. This characteristic allows the steel to be used in harsh conditions without the need for any coatings or paints on its surface.

ASTM A242 steel is a type of weathering steel, commonly referred to as Corten A. It is important to note that the A242 specification is limited to steel materials with a thickness of less than 4 inches (100 mm).

In summary, ASTM A242 steel is highly valued for its strength, durability, and aesthetic qualities, making it a favored option for both functional and decorative applications in outdoor environments.

Referred standards for ASTM A242 plates

ASTM A6/A6M standard specification for structural steels of hot rolled steel plate, profiles, beams, steel sheet pile, etc.
G101 Instructions for low alloy atmospheric corrosion resistant steels.

In case of welding works for A242 steel, it should follow the specification of A6/A6M appendix X3, the welding processes that suitable for this grade of steel.
Steel products like steel coil and without further heat treatment, should follow the additional requirements, includes testing methods in ASTM A6/A6M.

A242 steel plate chemical composition and mechanical properties

Chemicals:
C Max at 0.15%
Mn Mx at 1.00%
P Mx 0.15%
S Mx 0.05%
Cu Min 0.20%

If using other alloy elements, following elements are to be considered to add as required: Cr, Ni, Si, V, Ti and Zr.

Mechanical properties:
Different thickness has different requirements for tensile strength and yield strength
For tensile strength:
20 mm below: 70 Ksi or 480 Mpa
20 mm to 40 mm: 67 Ksi or 460 Mpa
40 mm to 100 mm: 63 Ksi or 435 Mpa
For yield strength:
345, 315 and 290 Mpa respectively.

Elongation for 50 mm specie is 21% and for 200 mm is 18%.

A242 steels applications

A242 steel plate can be used in the manufacture of vehicles, bridges, towers, construction of tanks, containers, frame structures, with requirements of welding, or bolted.

Test involved

Chemical analysis
Post weld heat treatment of mechanical test simulation
Charpy V-Notch Impact Test
Drop Weight Test (DWT)
Ultrasonic Examination
Measurement of reduction area

Octal provide ASTM A242 low alloy high strength steel plate as follow:
Standard: ASTM A242
Thickness Range: 6 – 100 mm
Width Range: 900 – 4800 mm
Length Range: 3000 – 12000 mm
Steel Cutting Services: Flame Cutting Steel, Laser Cut Steel, Waterjet cutting steel sheet, Plasma Cutting.

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