4340 HR Q&T
Chemical Composition
Carbon (C)              0.38%-0.43%
Manganese (Mn)      0.60%-0.80%
Silicon (Si)              0.15%-0.35%
Molybdenum (Mo)     0.20%-0.30%
Chromium (Cr)          0.70%-0.90%
Nickel (Ni)               1.65%-2.00%
Sulphur (S)              0.04% MAX
Phosphorus (P)         0.035% MAX
The physical properties of 4340 Q&T depend on how much tempering was done to the material and for how long. If you need to meet specific physical properties, please contact your Alro Sales Representative before ordering to make sure that this product will meet your requirements. 
Typical Uses
Typical uses for 4340 include:
  • Axle Shafts
  • Heavy Duty Shafting
  • Landing Gears
  • Machine Tool Arbors
  • Mine Drilling Parts
  • Power Transmission Gears
  • Trunnion Shafts

4340 Hot Rolled Quenched and Tempered Steel

AISI 4340 is a highly alloyed steel containing very high nickel and chromium content. This combination assures deep hardening when oil quenched and high strength characteristics throughout the section. 4340 HR Q&T is primarily used for heavily stressed parts that must operate under strenuous conditions. The Quenching boosts the hardness of the steel, while the tempering helps to make sure that it isn't too brittle to work with.
In addition to 4340, Alro also stocks Annealed quenched and tempered and Hot Rolled 4340.