THERMOLD H11 (formerly Thermold A1) is an air-hardening hot-work tool steel having high toughness and hot hardness at elevated temperature. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness and fatigue. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-243. Producer or source: Cyclops Corporation.