AISI No. 631 is chromium-nickel-aluminum precipitation hardening stainless steel recommended for aircraft, missile and jet engine parts. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-168. Producer or source: Alloy steel mills and foundries.