Crucible HiStar 40 is a prehardened mold steel having a hardness of 37-41 HRC and used for plastic or rubber molds. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on wear resistance as well as heat treating, machining, and joining. Filing Code: TS-609. Producer or source: Crucible Service Centers Divisional Headquarters.