Ferrium C69 is a case/core steel with a case hardness of 69 HRC and a core hardness of 50 HRC. It is used in racing applications, where rolling contact fatigue is an issue, and will be undergoing testing by the National Aeronautics and Space Administration (NASA) for aerospace gear applications. This datasheet provides information on hardness, and tensile properties as well as fatigue. It also includes information on forming and heat treating. Filing Code: SA-553. Producer or source: QuesTek Innovations, LLC.