PACIFIC 4340 is available in two conditions: heat treated (quenched and tempered) to high strength or annealed for ease of machining and subsequent heat treatment. It is a nickel-chromium-molybdenum medium carbon alloy steel with deep hardenability. It can be through hardened in large sections. When properly hardened, 4340 exhibits a good combination of strength, ductility and toughness; this is the material to which other ultra-strength steels are compared. PACIFIC 4340 Heat Treated bars are hardened to 285/331 HB and meet ASTM A 434, Class BD. 4340 is weldable but only with proper precautions; because of its high hardenability, it requires both preheat and post heat in virtually all welding applications. It can be induction hardened or nitrided after quenching and tempering.