FAGERSTA M-42 is a molybdenum super high-speed tool steel with a high carbon content and 8% cobalt. Its composition provides excellent cutting hardness and good hot-hardness characteristics. It is used widely for machining superalloys and steels that have been heat treated to Rockwell C 54. This datasheet provides information on composition and hardness. It also includes information on forming, heat treating, machining, and surface treatment. Filing Code: TS-327. Producer or source: Fagersta Steels Inc..