Weathering steels, also known by the trade name COR-TEN steels, are high-strength, low alloy steel with a carbon content of less than 0.2 percent by weight. It was originally developed in the 1930s by the United States Steel to prevent corrosion and abrasion in their ore wagons.
Weathering steel has a unique composition that imparts corrosion and weathering resistance into the steel. They eliminate the need for painting and have a rust-like appearance after several years of their life.
This article discusses the features and benefits of weathering steel in the construction industry.
Features of Weathering Steel
- Weathering steel is a steel alloy chemically composed of phosphorus, copper, nickel, silicon, and chromium that results in the formation of an adherent protective rust “patina” under a corrosive environment. This protective layer inhibits corrosion and further deterioration of the steel.
- When the rusting process is initiated in weathering steel, the alloy elements produce a stable layer called the patina that adheres to the base metal. Compared to the rust layers formed in other structural steel types, patina is less porous. This protective layer develops and regenerates with weather and impedes further access to oxygen, moisture, and pollutants.
- Weathering steel structures do not require painting. For instance, a bridge fabricated from unpainted weathering steel can achieve a design life of 120 years with nominal maintenance. Hence, a well-designed weathering steel structure is an attractive, low-maintenance, and economic option.
- Weathering steel is used to construct bridges, load-bearing structures, utility towers, guide rails, ornamental sculptures, facades, and roofing.
- Weathering steel is specified as per ASTM as A847, A588, A242, and A606. ASTM A847 is used for pipe and tube structures. A588 and A606 are new grades of weathering steel used for heavier gauge plates and lighter gauge plates, respectively.
Advantages of Weathering Steel
- High strength
- Low maintenance cost
- Easy installation
- No need for protective paint
- Cost-effective
- Provides unique design and appearance
- Environmental-friendly steel
Weathering steel is unsuitable for extreme marine environments, and humid subtropical climates as the patina continues to corrode instead of stabilizing the protective layer. Alternate wet and dry conditions are required for maintaining the patina layer. The absence of this condition results in a corrosion rate similar to ordinary structural steel. Weathering steel fabrication requires specialized welding.
FAQs
Weathering steel is a steel alloy chemically composed of phosphorus, copper, nickel, silicon, and chromium that results in the formation of an adherent protective rust “patina” under a corrosive environment.
When the rusting process is initiated in weathering steel, the alloy elements produce a stable layer called the patina that adheres to the base metal. Compared to the rust layers formed in other structural steel types, patina is less porous. This protective layer develops and regenerates with weather and impedes further access to oxygen, moisture, and pollutants.
Weathering steel is unsuitable for extreme marine environments, and humid subtropical climates as the patina continues to corrode instead of stabilizing the protective layer.
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