CORTEN / COR-TEN STEEL
Weathering steel, best-known under the trademark COR-TEN steel and sometimes written without the hyphen as "Corten steel",it is a group of steel alloys which were developed to eliminate the need for painting, and form a stable rust-like appearance if exposed to the weather for several years.
"Weathering" refers to the chemical composition of these steels, allowing them to exhibit increased resistance to atmospheric corrosion compared to other steels. This is because the steel forms a protective layer on its surface under the influence of the weather.
The corrosion-retarding effect of the protective layer is produced by the particular distribution and concentration of alloying elements in it including Chromium Copper Nickel & Vanadium. The layer protecting the surface develops and regenerates continuously when subjected to the influence of the weather. In other words, the steel is allowed to rust in order to form the 'protective' coating.
Weathering steel is popularly used in outdoor sculptures, architectural elements, bridges, cladding, facades and structural applications
BlueScope Steel manufactures an Australian version weathering steel called Lyten WR350