A steel alloy that develops a stable, rust-like surface when exposed to weather for several years, eliminating the need for painting. COR-TEN steel is often used for outdoor sculptures, for example, works by Richard Serra and Robert Indiana. The U.S. Steel corporation holds a trademark on the name COR-TEN, which is derived from two properties of the material: CORrosion resistance and TENsile strength. It is also known as weathering steel.

Barnett Newman. Broken Obelisk. COR-TEN steel. 1967. Neue Nationalgalerie, Berlin.