Salt bath ferritic nitrocarburizing of brake rotors

A brake rotor made according to a method comprising the steps of:

• casting a cast iron brake rotor having mutually opposed first and second rotor cheeks;
• providing a nitrocarburizing salt bath;
• providing an oxidizing salt bath;
• pre-heating the brake rotor to a first predetermined temperature;
• immersing the brake rotor into the nitrocarburizing salt bath, wherein the nitrocarburizing salt bath is at a second predetermined temperature, and wherein the brake rotor is placed into the nitrocarburizing salt bath such that all surfaces of the first and second rotor cheeks are in contact with the nitrocarburizing salt bath;
• removing the brake rotor from the nitrocarburizing salt bath after a first predetermined dwell time;
• immersing the brake rotor into the oxidizing salt bath, wherein the oxidizing salt bath is at a third predetermined temperature, and wherein the brake rotor is placed into the oxidizing salt bath such that all surfaces of the first and second rotor cheeks are in contact with the oxidizing salt bath;
• removing the brake rotor from the oxidizing salt bath after a second predetermined dwell time;
• and
• cooling the brake rotor to substantially room temperature;
• wherein the brake rotor made according to said method consists of pearlitic cast iron which, as a result of said method, the brake rotor has a ferritic nitrocarburized surface defined by a compound zone and a diffusion zone, wherein:
• said compound zone consists of an oxide layer consisting of Fe3O4;
• and generally subjacent said oxide layer, predominantly epsilon iron nitride Fe3N and a smaller volume of gamma prime iron nitride Fe4N;
• and
• disposed subjacent said compound zone, said diffusion zone consists of iron base ferrous material with a lower concentration of diffused nitrogen than that of said compound layer with the nitrogen in solid solution with the base ferrous material.