AISI 3140 is a nickel-chromium alloy steel of the oil hardening type. It has good hardenability and good toughness. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on heat treating, machining, and joining. Filing Code: SA-29. Producer or source: Alloy steel mills and foundries.