Something about 4340 alloy steel

*What is 4340 alloy steel?

4340 Alloy Steel is an iron-based alloy containing nickel, chromium, and molybdenum. The relatively high carbon content provides this alloy with superior strength in applications where severe service conditions exist. 4340 Alloy Steel has high strength, superior toughness, and good ductility.

*Is 4340 a low alloy steel?

AISI 4340 is a low alloy steel containing nominally 0.4% C, 0.8% Cr, 0.25% Mo, and 1.8% Ni. Higher strength levels up to 150 KSI 0.2% PS may be achieved by suitable heat treatment. Often used in preference to AISI 4140 at the higher strength levels because of its better hardenability and improved CVN impact toughness.

*How hard is 4340 annealed?

AISI 4340 is stocked in the heat treated and stress-relieved condition at approximately 150,000 psi (1034 N/mm2) and in the annealed condition at HB 235 max.