There are many kind of steel alloy. The common divisions are as follows. Usually according to the content of alloy elements steel alloy is divided into low steel alloy (content is under 5%), medium steel alloy (content is from 5% to 10%), high steel alloy (content is more than 10%);According to the quality steel alloy is divided into high quality steel alloy and excellent steel alloy ;According to the characteristic and the application steel alloy is divided into alloy structural steel, stainless steel, acid steel, wear-resistant steel, heat-resistant steel, alloy tool steel, bearing steel, alloy spring steel and special steel performance (such as soft magnetic, steel, permanent magnets, magnetic steel) etc.
In steel, except iron and carbon and small amounts of inevitable silicon, manganese, phosphorus, sulfur, it still contains a certain amount of alloy elements, alloying elements in steel with silicon, manganese, molybdenum, nickel, luo, vanadium, titanium, niobium, boron, tombarthite, this kind of steel is steel alloy. Steel alloy systems of all countries, along with their respective resources situation, are different from the conditions of the production and usage. In the past, the abroad developed nickel and luo steel systems, but our country develops silicon, manganese, vanadium, titanium, niobium, boron, lead, rare earth steel alloy systems.