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Weathering Steel

Weathering Steel


These high strength low carbon alloy steels, mainly proprietary, develop an attractive rust patina which serves as a protective barrier in harsh outdoor environments. Items manufactured using weathering steel require minimal maintenance. Ask us to assist you with weathering steel services.


The Concept of Weathering Steel

Weathering steel relies upon an ingenious concept. Manufacturers utilize a low amount of carbon and controlled quantities of specific alloy metals to create a type of high strength low alloy steel capable of resisting harsh outdoor conditions better than many other metals.

These products rust to create an attractive reddish or umber colored patina. This exterior layer serves as a protective outer barrier to further oxidation. The distribution and the concentration of the alloys within weathering steel contribute to the development of the patina.


Weathering Steel: Using a Rust Patina to Protect Metal Surfaces

Industrial items produced from weathering steels display an enhanced ability to withstand harsh outdoor environments. They will eventually corrode, of course, yet under specified weather conditions after an initial period of rusting, the protective exterior patina helps protect the underlying metal for a longer period of time than comparable high strength steel products enjoy. The composition of the alloys used in weathering steel produce this result: copper, chromium, and nickel play an especially significant role in forming the patina. However, manufacturers also frequently utilize chromium, manganese, and phosphorous as alloys in these products.

The effectiveness of the patina in adhering and protecting underlying metal surfaces hinges to some extent upon an alternating cycle of wet and dry weather (suitable for creating the initial rusting). Weathering steel may not perform optimally in highly polluted (and thus acidic) or salty maritime environments. After the creation of a complete patina layer, items produced from weathering steel usually require less maintenance, although rusting does remain ongoing.


A Brief History of Weathering High Strength Low Alloy Steel

The U.S. Steel Company developed the first weathering steel products in the United States during the 1930s. It sought to prevent the rapid deterioration of industrial railroad coal ore cars. The company developed a proprietary metal renowned for its corrosion resistance and high tensile strength, a product given the name “COR-TEN® steel”. Eventually, other manufacturers also developed types of proprietary weathering steel.

While initially used for industrial purposes, weathering steel also gained popularity for use in outdoor works of art. During the 1960s, designers began employing this material in both statuary and architecture. Finished in 1964, the John Deere World Headquarters Building in Moline, Illinois utilized weathering steel extensively. This metal produces a very attractive patina.

Weathering steel no longer receives widespread use in buildings in some places due to its dependence upon alternating dry and wet climatic conditions, and problems associated with acidic rain in polluted urban environments. However, it has found widespread use in many industrial settings, including as a construction material for shipping containers.


Some Properties And Characteristics of Weathering Steel

Weathering steel as a high strength low alloy steel usually displays high tensile strength and enhanced corrosion resistance. After initial rusting, the formation of a protective exterior patina helps safeguard the underlying metal against many environmental impacts. The metal surface obtains a characteristic reddish-umber color.

The Formation of a Protective Patina

During the formation of iron rust, the oxidation occurring upon exposure to oxygen and water typically causes changes in chemical composition which result in metal flakes loosening from the surface and falling away. While rusting remains ongoing in weathering steel also, the exterior patina formed from the rust continues adhering to the surface for a much longer period of time (due to the alloy composition of the metal). The patina in fact essentially forms a protective layer helping to retard further oxidative changes. In some locations, bridges constructed from this metal reportedly obtain impressive useful lifespans of up to 120 years.


Some Popular Types of Weathering Steel

The COR-TEN® designation remains a trademark of U.S. Steel. The ASTM, an international standards body, has officially listed this product as A 242 followed by the tradename. Additionally, U.S. Steel offers a COR-TEN® B product in thinner dimensions.

Several companies today reportedly also market A606-4 and A588 internationally as types of weathering steel. Some online sources suggest a proprietary metal called PATINAX® produced by ThyssenKrupp Steel Europe AG has also gained popularity as a weathering steel for some specific applications since 2014.


Weathering Steel Applications

Today weathering steel occurs in a number of economic sectors, particularly the industrial and transportation industries. It serves as a staple constituent of most modern shipping containers. The product has also obtained specific uses within the maritime sector, and as a popular medium for outdoor works of art.

In some locations, weathering steel serves as an excellent component of bridges. It offers the advantage of strength, coupled with extended durability and minimal maintenance requirements. For example, bridge builders can employ this material in locations where frequent applications of protective exterior coatings or paints would prove costly and inconvenient.


Some Advantages of High Strength Low Alloy Weathering Steel

Weathering steel offers a number of advantages for metal parts manufacturers. First, this material in certain locations supplies extended corrosion resistance. It furnishes a lengthier anticipated product lifespan than many other high strength steel metals.

Second, items utilizing weathering steel when utilized in appropriate environments won’t require a high level of exterior maintenance. The application of coats of protective materials or paints may become unnecessary. This factor may ultimately render weathering steel the most cost-effective metal to use in some products, particularly in items placed in remote or hard-to-access locations.

Third, as a construction material, this form of steel often permits more rapid building schedules. It requires only minimal exterior maintenance. People creating items from this type of high strength low alloy steel do not need to interrupt construction to coat the product with protective coatings designed to retard rusting, for example.

Contact Bunty LLC Today

For further information about our weathering steel capabilities, contact us via the convenient website form or submit a request for quote directly. We welcome your inquiries.

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From a contract manufacturing firm, BuntyLLC evolved into a full service custom machined, forged and cast metal parts fabrication enterprise. We supply global solutions from our headquarters in Greenville, South Carolina.

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