Available in COR-TEN® steel

Weathering steel, often referred to by the genericised trademark COR-TEN steel and sometimes written without the hyphen as corten steel, is a group of steel alloys which were developed to eliminate the need for painting, and form a stable rust-like appearance after several years' exposure to weather.

The surface oxidation of weathering steel takes six months, but surface treatments can accelerate the oxidation of weathering steel again to as little as one hour.[

The name COR-TEN refers to the two distinguishing properties of this type of steel: corrosion resistance and tensile strength.