En9 steel is a medium carbon steel grade having carbon content between 0.5 to 0.6 commonly supplied in the As Rolled condition. It is available in rounds, flats, hexagons and other forms. It is used in a number of engineering applications such as gears, sprockets and cams. Grades such as S55C, S53C are also types of En9 grade.
It can be flame or induction hardened to produce a high surface hardness with excellent wear resistance for a carbon steel grade.