AISI 4340

AISI 4340 steel / EN 24 is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. AISI 4340 is also one kind of nickel chromium molybdenum steels. 4340 alloy steels are generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa. Pre-hardened and tempered 4340 steels can be further surface hardened by flame or induction hardening and by nitriding. The 4340 steel has good shock and impact resistance as well as wear and abrasion resistance in the hardened condition. AISI 4340 steel properties offer good ductility in the annealed condition, allowing it to be bent or formed. Fusion and resistance welding is also possible with our 4340-alloy steel. ASTM 4340 material is often utilized where other alloy steels do not have the hardenability to give the strength required. For highly stressed parts it is excellent choice. AISI 4340 alloy steel can also be machined by all customary methods.

Applications for AISI 4340 steel

AISI 4340 / EN 24 steel is used in most industry sectors for applications requiring higher tensile/yield strength than 4140 steels can provide.

Some typical applications such as

  • Aircraft Landing Gear
  • Automotive,
  • Oil and Gas Drilling,
  • Forging,
  • Warm and Cold Forming,
  • Machine Building,
  • Transfer Systems, like power transmission gears and shafts.
  • General engineering industries and structural use applications, such as: heavy duty shafts, gears, axles, spindles, couplings, pins, chucks, moulds etc.

    • USA

    ASTM
    A29

    4340

    Britain

    EN
    10250

    36CrNiMo4/1.6511

    Japan

    JIS
    G4103

    SNCM 439/SNCM8

    Britain

    BS
    970

    EN24/817M40

    Grade C Mn P S Si Ni Cr Mo
    4340 0.38 - 0.43 0.60 - 0.80 0.035 0.040 0.15 - 0.35 1.65 - 2.00 0.70 - 0.90 0.20 - 0.30
    36CrNiMo4/1.6511 0.32 - 0.40 0.50 - 0.80 0.035 0.035 ≦ 0.40 0.90 - 1.20 0.90 - 1.2 0.15 - 0.30
    EN24/817M40 0.36 - 0.44 0.45 - 0.70 0.035 0.040 0.1 - 0.40 - 1.00 - 1.40 0.20 - 0.35
    SNCM 439/SNCM8 0.36 - 0.43 0.60 - 0.90 0.030 0.030 0.15 - 0.35 1.60 - 2.00 0.60 - 1.00 0.15 - 0.30