More than 90% of vanadium production is used in iron and steel alloys. Structural steels contain between 0.03% and 0.2% vanadium. This little addition of vanadium improves the mechanical properties of the steels. As a matter of fact, vanadium steels are also used in special places such as locomotive constructions, parts of aircraft engines, springs and gears and so on. Steels containing vanadium up to 4% are tool steels. Their hardness, strength and durability are high.