Allegheny Ludlum type 309 is a chromium-nickel, austenitic, heat and corrosion resisting steel recommended for high-temperature applications in corrosive environments. It is intended primarily for high-temperature applications at 816 C (1500 F) or higher, where resistance to oxidation and/or corrosion is required. 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 high temperature performance and corrosion resistance as well as forming and heat treating. Filing Code: SS-728. Producer or source: Allegheny Ludlum Corporation.