300M Steel

UNS K44220 low_alloy_steel
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Modified 4340 with Si and V additions, vacuum arc remelted for ultra-high strength (≥1930 MPa). Primary material for commercial aircraft landing gear forgings.

Applicable Standards

  • AMS 6417
  • AMS 6257
  • MIL-S-8844

Composition Ranges (wt %)

Element Min (%) Max (%) Typical Range
Fe 93.0 97.0 ~95.0
Si 1.45 1.8 ~1.62
Ni 1.65 2.0 ~1.82
Cr 0.7 0.95 ~0.82
Mo 0.3 0.45 ~0.38
C 0.4 0.46 ~0.43
V 0.05 0.1 ~0.08
Fe 93.0–97.0% Si 1.45–1.8% Ni 1.65–2.0% Cr 0.7–0.95% Mo 0.3–0.45% C 0.4–0.46% V 0.05–0.1%

Typical Applications

  • Commercial aircraft landing gear
  • Military aircraft forgings
  • Ultra-high-strength structural components
  • Drive shafts
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