These steels have a quite low carbon content, generally not exceeding 0,2%, and as lower as the customer desires in order to obtain the core of the cemented pieces ductile and tough. Other elements may or may not be present (Ni, Cr, Mo, Mn) with the specific purpose of giving strength and toughness to the core of the piece. They are mainly used in the construction of mechanical parts subject to wear, such as gears, pins, bushes, trees, etc.
The thermochemical treatment characterizes these steels. It consists in promoting a carbon enrichment of the outermost layer of the material, making it particularly hard after the following treatment of quenching and tempering at 150º C approx.
Examples of case hardening steels: C10E, C10R, C15E, C15R, 16MnCr5, 16NiCr4, 17NiCrMo6-4.