The main alloying elements of alloy steel are silicon, manganese, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, aluminum, copper, boron, rare earth and so on. Among them, vanadium, titanium, niobium, zirconium and so on in the steel is a strong carbide forming elements, as long as there is enough carbon, under appropriate conditions, can form their own carbides, when the lack of carbon or high temperature conditions, Manganese, chromium, tungsten, molybdenum for the formation of carbide elements, part of the atomic state into the solid solution, the other part of the formation of replacement alloy cementite; aluminum, copper, nickel, cobalt, silicon, etc. is not formed Carbide elements, usually in the atomic state in the solid solution.