About 86% of molybdenum produced is used in metallurgical applications such as alloys, with the rest of molybdenum used as compounds in chemical applications. Estimated fractional global industrial use of molybdenum is structural steel 35%, stainless steel 25%, chemicals 14%, tool & high-speed steels 9%, cast iron 6%, molybdenum elemental metal 6%, and superalloys, 5%.
The ability of molybdenum to withstand extreme temperatures without significantly expanding or softening makes it useful in applications that involve intense heat, including the manufacture of armor, aircraft parts, electrical contacts, industrial motors and filaments.
Most high-strength steel alloys (example 41xx steels) contain 0.25% to 8% molybdenum.Despite such small portions, more than 43,000 tonnes of molybdenum are used as an alloying agent each year in stainless steels, tool steels, cast irons and high-temperature superalloys.
Molybdenum is also used in steel alloys for its high corrosion resistance and weldability.Molybdenum contributes further corrosion resistance to “chrome-moly” type-300 stainless steels (high-chromium steels that are corrosion-resistant already due to their chromium content, but in reality “chrome-moly” is not a type-300 stainless, but instead a 41xx series that is not stainless) and especially so in the so-called superaustenitic stainless steels (such as alloy AL-6XN). Molybdenum acts by increasing lattice strain, thus increasing the energy required to dissolve out iron atoms from the surface.