In addition to iron and carbon, other alloy elements are added to steel, so it is called alloy steel. Alloy steel is an iron-carbon alloy formed by adding an appropriate amount of one or more other metal elements on the basis of ordinary carbon steel. Various added metals and proper processing techniques can make alloy steels with different special properties such as high strength, high toughness, wear resistance, corrosion resistance, low-temperature resistance, high-temperature resistance and non-magnetism.