4340 Modified 300M Vac Melt N&T (Normalized & Tempered) is an aircraft quality extremely high strength 4340 alloy with the addition of Vanadium and a higher Silicon & Molybdenum content to make it stronger and tougher. The product is then normalized and then tempered for stress relief. This material is melted in an Electric Furnace, and then remelted via Consumable Electrode Vacuum Arc Remelting. This produces a much cleaner steel meeting the magnetic particle test requirements of AMS-2300. This alloy exhibits deep hardenability, high ductility, toughness and strength. The material has high fatigue resistance and creep resistance. After tempering, flame or induction hardening will produce material with Rc 52 minimum. 4340 is used in products such as airframe parts, landing gears, and missile components. (UNS K44220)
