4340

4340 (UNS G43400, EN 1.6565) is a high-grade alloy steel known for its strength, toughness, and wear resistance. 4340 is composed of iron (Fe) and contains ~0.4% carbon (C), 0.8-1.1% chromium (Cr), 1.65-2.0 % nickel, and ~0.25% molybdenum (Mo). 4340 is highly versatile in terms of hardened and strengthened via heat treatment, and is magnetic.