November 16, 2018

GKHW Bar

Increasing numbers of industrial components are being subjected to high surface stresses and dynamic loads, requiring the use of special high-performance steels. Where high surface hardness and excellent fatigue strength are required and when the material is also subjected to high temperatures, nitriding technology offers the best case hardening option.

FOR REQUIREMENTS: High Fatigue Nitriding Grade
MELT PRACTICE: ESR
CORROSION RESISTANCE: N/A
ALTERNATIVE TO: M-50
Nitralloy N/135
SPECIFICATIONS: 33CrMoV12-9
UNS: K24340


In this field, GKHW offers the best combination of core properties to withstand structural loads & damage tolerances and surface functions in the case hardened layer. The result on components gives one of the best solutions in the market for contact pressures and fatigue performances.

GKHW can also be used without nitriding and offers the triple advantage of an excellent combination of mechanical properties, high thermal fatigue and high thermal conductivity.

Benefits of GKHW

The use of GKHW covers all the gears design considerations and brings the highest value of this technology:

  • Exceptional fatigue bending performance
  • Very deep case requirement (0.8mm achieved in 120Hrs nitriding)
  • Limited influence of ageing during nitriding on core properties
  • Exceptional compromise of core hardness and damage tolerance
  • Surface metallurgy with limited depth and favorable compound layer
  • Weldable material (EBW for instance) giving the opportunity to avoid mechanical assembly

Typical Applications

GKHW is used to produce nitrided parts which need to be extremely stable after hardening and tempering. It is particularly suitable for producing parts that undergo special nitriding.

GKHW has been successfully used for decades in the most critical mechanical components within Aerospace, Motorsports, injection systems, firearms, retaining rings, etc.

  • Gears, spindles, machine-tool fittings
  • Crankshafts, precision parts, aircraft parts
  • Thrust rings, bearing races working up to 400 °C

Comparisons to Other Materials

Grade Technology   Case properties Core properties Lf case hardened material (Mpa/KSI)
Operating temperature (°F) Top hardness (HRC) Case depth (mm/in) UTS (Mpa/KSI) YS0,2 (Mpa/KSI) K1c (MPa.Vm)
9310 Remelted Carburizing 300 60 1.40/.055 1150/167 900/131 120 1050/152
AMS 6308 390 60 1.40/.055 1172/170 965/140 126 /
AMS 6509 840 62.5 1.40/.055 1578/229 1370/199 93 /
AMS 6475 Deep nitriding 840 65.50 0.45/.018 1240/180 1150/167 / /
GKHW 840 64.70 0.70/.028 1250/181 1060/154 180 1140/165
  Heat Treatment UTS 0.2% YS E KV Surface Hardness
    (MPa / Ksi) (MPa / Ksi) (%) (J /ft.lb) HRC
M50 VIM/VAR 1100°C / Gas, -75°C, 3 x 550°C   Through hardened to HRC: 60 – 63  
9310 VAR & VIM/VAR 825°C / Oil, -75°C, 150°C 1150/167 900/131 14 140/103 60
M50NIL 1100°C / Oil, -75°C, 3 x 540°C 1400/203 1200/174 15 12/9 60
GKH Remelt (W) & VIM/VAR (YW) 920°C, Oil, 600°C 1250/181 1060/154 15 130/96 65.5
  920°C, Oil, 640°C 1080/157 900/131 19 170/125 65.5
GKP Remelt (W) & VIM/VAR (YW) 940°C, Oil, 600°C 1430/207 1280/186 14 50/37 67
  940°C, Oil, 640°C 1250/181 1075/156 16 80/59 67

Chemical Composition

  C Si Mn S P Ni Cr Mo V
min. 0.29 0.10 0.40 / / / 2.80 0.70 0.15
max. 0.36 0.40 0.70 0.005 0.015 0.30 3.30 1.20 0.35

Stocking Sizes

Bar: 5.512″ & 6.299″ (140mm & 160mm)

> Our Current Stock Summary

Datasheet and Brochure



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