4340 is a low alloy steel that is used in downhole tools and hangers that require very high strength with excellent impact resistance. It is a heat treatable alloy steel that contains nominally .40% Carbon, with Nickel, Chromium, and Molybdenum as the primary hardening elements.
The Nickel content affords this alloy the ability to exhibit excellent impact properties at room temperature and lower. It is also one of the deeper hardening low alloy steels available.
This alloy is not recommended for applications that involve exposure to Hydrogen Sulfide, in accordance with NACE MR-01-75/ISO-15156.
105,000 psi minimum yield - 321 Brinell max surface hardness
Annealed or As-rolled - no mechanical properties; suitable for further heat treatment