AK Steel 309S is a chromium-nickel austenitic stainless steel that provides excellent corrosion resistance and heat resistance in addition to good strength at room and elevated temperatures. It is identical to AK Steel 309 except for a lower carbon content that minimizes carbide precipitation and improves weldability. 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-1334. Producer or source: AK Steel Corporation.