AISI 4340 is a 1.8% nickel - chromium - molybdenum high hardenability high tensile steel - generally supplied hardened and tempered in the tensile range of 930 - 1080 Mpa (condition U) - (Rc 28 - 36)..

Characterised by high strength and toughness in relatively large sections.

Pre hardened and tempered 4340 can be further surface hardened by flame or induction hardening and by nitriding.

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

Typical applications are: Heavy Duty Shafts, Gears, Axles, Spindles, Couplings, Pins etc.