Abstract ATI 690 is a nickel-chromium-iron alloy that is intended for the production of nuclear grade tube that meets the requirements outlined in ATI 690 Alloy TREX, ATI, 2012. This alloy exhibits excellent resistance to many corrosive aqueous media and high temperature atmospheres. In addition to its corrosion resistance, ATI 690 has high strength, good metallurgical stability, and favorable fabrication characteristics. This datasheet provides information on composition, physical properties, microstructure, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-771. Producer or source: ATI.