About 80% of world vanadium production goes into steelmaking, but it is also an important constituent of certain high performance non-ferrous aerospace alloys. It is usually added to steel as a ferro-alloy (FeVa).
In steel, vanadium increases tensile strength, toughness and fatigue resistance, as well as improving the hardenability of some grades and conferring rust resistance. An early application was armour plate.
Today, vanadium’s main applications are in high-strength low-alloy sheet for the automotive sector, in engineering steels – such as for axles, crankshafts and gears – and in spring and high-speed tool steels. In stainless steels it is typically used for producing grades needed for applications like surgical instruments. And for more detail click and see wikipedia entry.