Alloy steel refers to the addition of other alloying elements besides iron and carbon to steel, which is called alloy steel. A ferrocarbon alloy formed by adding an appropriate amount of one or more alloying elements on the basis of ordinary carbon steel. By adding different elements and adopting appropriate processing techniques, special properties such as high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance, high temperature resistance, and non-magnetic properties can be obtained.

The main alloying elements of alloy steel include silicon, manganese, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, aluminum, copper, boron, rare earth, etc.

Vanadium, titanium, niobium, zirconium, and other elements are strong carbides forming elements in steel. As long as there is enough carbon, under appropriate conditions, they can form their own carbides. When carbon is lacking or under high temperature conditions, they enter the solid solution in an atomic state; Manganese, chromium, tungsten, and molybdenum are elements that form carbides, with some entering the solid solution in an atomic state and the other forming a displacement type alloy carbides; Aluminum, copper, nickel, cobalt, silicon, and other elements do not form carbides and generally exist in solid solutions in an atomic state.