Abstract AISI 1040 is a medium-carbon steel used in the hot-rolled, normalized, oil quenched and tempered or water quenched and tempered condition for general purpose engineering and construction. It provides medium strength and toughness at low cost. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CS-41. Producer or source: Carbon and alloy steel mills.