The Corten A weathering carbon steel coil is a high strength low alloy steel formulated with copper, chromium, nickel and phosphorus to develop a stable, self-protecting patina when exposed to atmospheric conditions. Unlike ordinary carbon steel that continues to corrode, the Corten A surface forms a dense oxide layer that slows further corrosion to a negligible rate, eliminating the need for painting in many architectural and structural applications. This makes the material