Cor-Ten® is United States Steel Corporation (USS) trade name for an atmospheric corrosion resistant steel it developed to be used where higher strength and longer life cycle material were desired. These steels naturally form a layer of rust or patina when exposed to various atmospheric conditions. This patina is what the guards this material against future corrosion. As Cor-Ten® became more popular over the years other producing mills began to develop their own atmospheric corrosion resistant steel. Therefore, ASTM stepped in a created what is considered equivalent specifications to Cor-Ten® in most applications.
The applicable equivalent ASTM specifications are