4140 steel is a 1% chromium-molybdenum general-purpose high-strength steel, usually hardened and tempered in the tensile range of 850-1000 Mpa. 4140 steel has improved machinability, which greatly increases feed and speed, while extending tool life without affecting mechanical properties. The prehardening and tempering 4140 can be further case hardened by flame or induction hardening and nitriding. AISI4140 steel bars have high strength, hardenability, good toughness, small deformation during quenching, and high creep strength and durable strength at high temperatures.