Aircraft Alloys / 4340 VAC MELT N&T

4340 Vac Melt N&T (Normalized & Tempered) is an aircraft quality extremely high strength medium carbon low alloy steel that has been 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 50, while nitriding will produce Rc 60. 4340 is used in products such as piston pins, bearings, ordnance, gears, dies, and pressure vessels. (UNS G43406)

Chemical Makeup

Element Min Max
Carbon, C 0.38 0.43
Manganese, Mn 0.65 0.85
Silicon, Si 0.15 0.35
Phosphorus, P - 0.01
Sulfur, S - 0.01
Chromium, Cr 0.7 0.9
Molybdenum, Mo 0.2 0.3
Nickel, Ni 1.65 2
Copper, Cu - 0.35
Aluminum, Al 0.02 0.05
Vanadium, V 0.02 0.08
Columbium/Niobium, Nb 0.02 0.05

Common Applications

  • Aerospace Aerospace
  • Defense Defense
  • Industrial Industrial


  • Extremely High Strength
  • Deep Hardenability
  • High Ductility
  • High Fatigue Resistance
  • High Creep Resistance

We stock 4340 VAC MELT N&T to the following specifications:

  • AMS-2300
  • AMS-6414
  • AMS-6415
  • AMS-6484
  • AMS-S-5000
  • BMS-7-28
  • BPS-299-947-055
  • DMS-1555 GRD A (CAP OF)
  • MIL-S-5000
  • MIL-S-8844 CL 1

Click on a cross-section to see the sizes we stock:

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