AISI 4620 is a nickel-molybdenum case hardening steel recommended where high core toughness and shock resistance are required. This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on low temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-63. Producer or source: Alloy steel mills and foundries.