Corten is a weathering steel. This material is a corrosion resistant steel, that left uncoated develops an outer layer patina. This patina protects the steel from additional corrosion. It is a high strength steel alloy, and it is used where higher strength and longer life cycle material are desired. Especially in situations where untreated alloys are desired.

The applicable equivalent ASTM specifications are A588GR A/B/K SPA-H 09CuPCrNi-A S355JOW/S355JOWP Q355GNH 09CrCuSb , which Central Steel Service supplies in various products including, sheet, coil, plate, steel flats, angles, channels, pipe and tube.