AISI 4340

Nickel, Chromium, Molybdenum steel for applications requiring high tensile strength and toughness values, particularly in large cross sections in the quenched and
tempered condition. The addition of Molybdenum prevents the steel from being susceptible to temper brittleness. Higher tensile and yield strength than 4140.

Configure & Buy

Product Features

  • Hardenability: good
  • Machinability: good
  • Strength: good

Technical Data

C Si Mn Ni Cr Mo S P
0.40 0.25 0.70 1.80 0.80 0.25 0.02 0.02
Forge Normalize Anneal Stress Relieve Harden Temper Nitride
850-1050 °C, slow furnace cool. 850-880 °C, air cool. 650-700 °C, Cool slowly in controlled furnace. In the quenched and tempered condition, about 30-50 °C below the tempering temperature. Air cool. In the annealed condition, 600-650oC. Air cool. 830-860 °C, oil quench 540-680 °C hold for 1 hour (min). at temperature, air cool. (see tempering chart). Suitable for both liquid and gas nitriding.
AS DIN BS AISI
4340 1.6565 EN24 4340