Tungsten — The Extreme Metal

Tungsten (from Swedish tung sten, meaning 'heavy stone') was identified in 1781 by Carl Wilhelm Scheele and first isolated in 1783 by the Elhuyar brothers in Spain. Its extreme hardness was exploited in the late 19th century when tungsten carbide was developed as a cutting tool material. Thomas Edison experimented with tungsten filaments for light bulbs, and by 1910, William David Coolidge developed a process for making ductile tungsten wire, enabling the modern incandescent lamp.

Tungsten has a density of 19.3 g/cm3 (nearly identical to gold), melting point of 3422 degC, and boiling point of 5555 degC — both the highest of any metal. Elastic modulus is 411 GPa, about twice that of steel. Tensile strength of drawn tungsten wire can exceed 1500 MPa. Tungsten has the lowest coefficient of thermal expansion of any pure metal and excellent resistance to creep at high temperatures. It transitions from ductile to brittle behavior (DBTT) at around 200-400 degC depending on processing.

Cemented tungsten carbide (WC-Co) is the dominant cutting tool and wear part material, used in metal cutting inserts, mining drill bits, and rock drilling. Tungsten heavy alloys (W-Ni-Fe, W-Ni-Cu) serve as counterweights, radiation shielding, and kinetic energy penetrators. Pure tungsten wire and rod are used for furnace heating elements operating up to 2500 degC, welding electrodes (TIG/GTAW), and electron emitters. Tungsten is also used in superalloys, electrical contacts, and as an alloying element in high-speed tool steels.

Highest melting point of any element enables use in extreme thermal environments. Exceptional hardness and wear resistance in carbide form. Very high density makes it effective for radiation shielding and ballistic applications. Lowest thermal expansion coefficient of any pure metal provides dimensional stability. High elastic modulus enables stiff structures.

Extremely difficult to machine in pure form — typically shaped by powder metallurgy (pressing and sintering) rather than conventional metalworking. Brittle at room temperature in polycrystalline form (DBTT issue). Very high density is a disadvantage in weight-sensitive applications. Limited availability — China controls approximately 80% of global tungsten supply. Oxidizes rapidly above 400 degC in air, requiring inert or vacuum atmospheres for high-temperature service.

Tungsten is widely recycled, especially from cemented carbide tools. The zinc reclamation process dissolves the cobalt binder, allowing tungsten carbide powder to be recovered and reused. Hard scrap and used drill bits have well-established collection networks. Approximately 30% of global tungsten supply comes from recycled sources.