4340 Steel

UNS G43400 low_alloy_steel
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Nickel-chromium-molybdenum high-strength low-alloy steel with excellent deep hardenability. The standard material for aircraft landing gear and highly stressed rotating shafts.

Applicable Standards

  • AMS 6415
  • AMS 6414
  • ASTM A29
  • MIL-S-5000

Composition Ranges (wt %)

Element Min (%) Max (%) Typical Range
Fe 94.0 98.0 ~96.0
Ni 1.65 2.0 ~1.82
Cr 0.7 0.9 ~0.8
Mo 0.2 0.3 ~0.25
Mn 0.6 0.8 ~0.7
C 0.38 0.43 ~0.41
Fe 94.0–98.0% Ni 1.65–2.0% Cr 0.7–0.9% Mo 0.2–0.3% Mn 0.6–0.8% C 0.38–0.43%

Typical Applications

  • Aircraft landing gear
  • Structural bulkheads
  • High-strength shafts and gears
  • Armour plate
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