Abstract CRUCIBLE 309 is a non-hardenable austenitic chromium-nickel steel that has high heat-resisting characteristics. In the annealed condition it is non-magnetic or magnetic, depending on the composition. When cold worked it is very slightly magnetic. Typical applications include aircraft heaters and sulfite liquor handling equipment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance as well as heat treating, machining, and joining. Filing Code: SS-405. Producer or source: Crucible Specialty Metals Division, Colt Industries.