Remedial measures include the sealing of crevices, blast cleaning to remove the rust ‘patina’ and repainting either in part or of the whole bridge. Alternatively, the steelwork can be enclosed in a proprietary system.
With corten steel, the rusting process starts in the same way, but the specific alloy elements in the steel produce a stable rust layer, which adheres to the base metal and has fewer pores. This rusty "copper rust" forms under alternate wetting and drying conditions, creating a protective barrier that prevents further entry of oxygen, water and pollutants. The result is that the corrosion rate is much lower than that of other structural steels. The mechanical properties and weathering rate depend on the alloys found in the steel, the concentration of these alloys and the thickness of the steel substrate.
Composition of Corten Steel
As a low carbon steel, corten steel usually has less than 0.3% carbon by weight. This small amount of carbon keeps it tough and tough. Weatherproof steel also includes other alloying elements, which help to improve strength, but more importantly, corrosion resistance. Many different alloying elements are used, but the three key elements in weathering steel are nickel, copper and chromium.
How does corten steel grade work?
Corten steels differ from other corrosion resistant steels, such as austenitic stainless steel, in resisting the formation of rust. Corten steel will rust, but the outer surface will only rust. Once the outer layer of rust is formed, the rust will not penetrate into the corten steel. The anti-rust layer on the surface acts as a barrier to prevent further corrosion of steel. In ordinary carbon steel, the rust layer formed is porous and will fall off, which allows another layer to form deeper in the steel. This cycle repeats until the steel becomes useless. In corten steel, alloying elements make the initial rust layer formed better adhere to the steel, prevent the corrosion from penetrating deeper and weaken the steel. This antirust coating does not need to be coated with weatherproof steel.
Classification of Corten Steel
Corten steel is a series of low carbon alloy steel, which is composed of many brands. Certain grades are proprietary, such as COR-TEN A or COR-TEN B.Patinax weathering steels, which are another group of proprietary grades. All these proprietary levels are similar to ASTM classifications A 242 and A 588.
When will corten steel be used?
Made of corten steel, weatherproof steel is often used in exposed steel structures because it can be more durable than ordinary carbon steel in outdoor conditions. This eliminates the need for continuous re-painting and re-painting of steel. Examples include building and bridge construction. The corrosion rate is slowed down enough by the anti-rust coating to make the corrosion amount considered unsafe. For other reasons, the structure has exceeded its design life.
Corten steel should not be used in some environments because corrosion resistance cannot withstand these conditions. Corten steel should not be used in environments with high chlorine content because the rust-proof layer can not withstand a large number of corrosive substances in environments rich in chlorine. This may lead to premature failure. Corten steel should not be used in applications that may cause electrochemical corrosion or corrosion due to extreme pH values.
Development History of Corten Steel
In 1933, American Iron and Steel Corporation developed and obtained a patent for steel with excellent mechanical resistance, mainly for railway funnel trucks, for handling heavy bulk cargo, including coal, metal ore, other mineral products and cereals. The most well-known controlled corrosion of this material was a welcome benefit discovered shortly after, prompting USS to apply for the trademark Cor-Ten. Because of its inherent toughness, this steel is still widely used in bulk transport and storage containers.
Remedial measures of corten steel
Carbon Steel, Corten Steel, Stainless steel
Rust, Bare, Powder Coated, Polished, Black Heat-resisting Paint, Iron Oxide
Diameter : 320mm--1200mm
Thickness : 1.2mm--3.0mm
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