Crucible CPM Rex 54 is a high-speed tool steel with cobalt added to improve red hardness. It is often used as an upgrade over grades M4 and M35. This datasheet provides information on composition, physical properties, microstructure, hardness, and elasticity. It also includes information on forming, heat treating, and surface treatment. Filing Code: TS-608. Producer or source: Crucible Service Centers Divisional Headquarters.