Heppenstall 6H55 is a medium carbon, alloy tool steel recommended for dies, gears, and shafting where toughness and abrasion are factors of performance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-151. Producer or source: Midvale-Heppenstall Company.