Abstract ONTARIO is an air-hardening die steel of the high-carbon high-chromium type. It has high hardness, high resistance to abrasion and excellent nondeforming characteristics. It is suited for a wide range of applications in which high abrasion resistance must be combined with high compressive strength and safety in hardening. Typical uses are cold-forming dies, forming rolls, thread-rolling dies, slitters and gages. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-323. Producer or source: AL Tech Specialty Steel Corporation.