Aircraft Alloys / NITRIDING HT (BHN 241-285)

Nitriding (135) Heat Treated is a chrome-moly alloy with the addition of aluminum to provide an extremely hard case with a strong ductile core when nitrided. This material comes quenched and tempered giving it an as shipped hardness of 241-285 BHN. This alloy is specifically designed for parts that require a nitriding treatment which provides a high surface hardness that stands up to wear, abrasion and heat distortion. Nitriding is a heat treatment method that hardens the outer surface of a metal by diffusing nitrogen into it under heat. Nitriding is a preferred hardening method for many parts used by the automotive, firearms, aerospace and tool-making industries. These parts include crankshafts, bolts, aircraft gears and pinions. (UNS# K24065)

Chemical Makeup

Element Min Max
Carbon, C 0.38 0.43
Manganese, Mn 0.5 0.8
Silicon, Si 0.2 0.4
Phosphorus, P - 0.025
Sulfur, S - 0.025
Chromium, Cr 1.4 1.8
Molybdenum, Mo 0.3 0.4
Nickel, Ni - 0.25
Copper, Cu - 0.35
Aluminum, Al 0.95 1.3

Common Applications

  • Aerospace Aerospace
  • Industrial Industrial


  • High Surface Hardness
  • Minimal Heat Distortion

We stock NITRIDING HT (BHN 241-285) to the following specifications:

  • AMS-2301
  • AMS-2304
  • AMS-6472
  • AMS-S-6709
  • ASTM-A-322
  • MIL-S-6709 A

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

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