AK Steel 309 is a chromium-nickel austenitic stainless steel. It is typically used for elevated temperature applications. Its high chromium and nickel contents provide comparable corrosion resistance, superior resistance to oxidation, and the retention of a larger fraction of room temperature strength than the common austenitic stainless steels, such as type 304. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-1333. Producer or source: AK Steel Corporation.