ATI 309S (UNS S30908) is a chromium-nickel austenitic stainless steel that is typically used for elevated-temperature applications. The alloy’s 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 alloys such as Type 304. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, machining, and joining. Filing Code: SS-1318. Producer or source: ATI.