Abstract 1045, 1045H, 1046, C45, C45E, and C45R are wrought medium-carbon (carbon = 0.42–0.51%) non-alloy steels that are used in the normalized, cold worked, or quenched and tempered condition. 1045, 1045H, 1046, C45E, and C45R may also be flame or induction hardened, nitrided, or nitrocarburized. These steels are widely used for moderately and highly stressed parts that require higher strength levels than can be achieved by the lower carbon grades, and where the expense of an alloy steel is not justified. Owing to their low hardenability their use in the quench hardened and tempered condition is not recommended for large sizes as the improvement in mechanical properties over the normalized condition is insufficient to justify the additional cost of heat treatment. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming and heat treating. Filing Code: CS-247. Producer or source: Heat Treater's Guide.