Abstract AISI No. 670 is a ductile cobalt-base alloy developed for high temperature service. It has exceptional mechanical properties at temperatures up to 1800 F. It is recommended for highly stressed parts operating at high temperature levels, such as in gas turbines and jet engines. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness, creep, and fatigue. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Co-47. Producer or source: Alloy steel mills and foundries.