Pure Tungsten
Unalloyed tungsten is 99.95 % or purer metal pressed and sintered from powder, then rolled, swaged or drawn. It has the highest melting point of any metal (3,422 °C), a density of 19.3 g/cm³, a modulus of 400 GPa and the lowest vapor pressure and thermal expansion (4.5 ppm/K) of the refractory metals. The price of that is brittleness: below its ductile-to-brittle transition, roughly 200–400 °C for wrought stock and higher once recrystallized, it cracks rather than bends.
Popular pure tungsten grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Pure W | 700 | 800 | 19.25 | Not recommended | Not recommended | Furnace hardware, targets, anodes |
| W (99.95% CP Tungsten) | 750 | 950 | 19.25 | Not recommended | Not recommended | Purity-specified rod, sheet and plate |
| EWP (WP) | 750 | 1,100 | 19.25 | Not recommended | Poor | Pure TIG electrode for AC aluminum welding |
All 3 pure tungsten grades
Choose pure tungsten for
Parts that run above 1,600 °C in vacuum, hydrogen or inert gas — heating elements, crucibles for sapphire and quartz growth, sintering boats, hot-zone shields — plus sputter targets, X-ray anodes, electron emitters, ion-implanter components and pure-tungsten TIG electrodes, wherever contamination from a binder or alloying element cannot be tolerated.
Look elsewhere when
The part is a counterweight or shield that must be machined, threaded or dropped without shattering (WHA-90 or WHA-95), it is a wear or cutting surface (WC-6Co or WC-10Co), it sees air above 500 °C (a platinum alloy, ceramic or coated molybdenum), or molybdenum does the job at half the density and a fraction of the difficulty below about 1,600 °C (Pure Mo, TZM).
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Pure tungsten by application
- Vacuum-furnace hot zones
- Pure W for heating elements, crucibles and the innermost shields above the range of molybdenum — crucibles for sapphire and quartz growth run at 2,000–2,100 °C.
- Targets, anodes and emitters
- Pure W and W (99.95% CP Tungsten) sputter targets, X-ray rotating-anode tracks (often with a few percent rhenium added), electron-beam filaments and ion-implanter parts.
- TIG electrodes
- EWP (WP) for AC welding of aluminum and magnesium; for DC steel and stainless work, and longer life on AC, the doped electrodes EWLa-1 (WL15) and EWZr-1 (WZ8) have largely replaced it.
Working with pure tungsten
- Machining
- Cut with carbide or diamond tooling at low feed and moderate speed, or by wire and sinker EDM, which is the safer route for any complex shape. Chamfer every edge, avoid sharp internal corners and thin unsupported sections, and expect chipping at exits. Warming the stock to 200–300 °C helps on heavy cuts.
- Forming
- Sheet and wire are bent and formed only warm — 300–600 °C for sheet, hotter for heavy sections — and only in the wrought, unrecrystallized condition. Recrystallized tungsten is brittle at any practical forming temperature.
- Joining
- Rivet, bolt or interlock. Brazing to molybdenum or steel with nickel- or copper-based fillers works for furnace assemblies; fusion welding is done only by electron beam in vacuum and leaves a brittle recrystallized zone. Tungsten oxidizes rapidly above 500 °C in air, so all hot service is under vacuum, hydrogen or argon.
Other tungsten alloy series
Pure Tungsten — frequently asked
What is pure tungsten?
Unalloyed tungsten is 99.95 % or purer metal pressed and sintered from powder, then rolled, swaged or drawn. It has the highest melting point of any metal (3,422 °C), a density of 19.3 g/cm³, a modulus of 400 GPa and the lowest vapor pressure and thermal expansion (4.5 ppm/K) of the refractory metals. The price of that is brittleness: below its ductile-to-brittle transition, roughly 200–400 °C for wrought stock and higher once recrystallized, it cracks rather than bends.
Which grade of pure tungsten should I use?
Pure W for machined rod, plate and sheet parts: furnace boats, crucibles, heat shields, sputter targets, X-ray and electron-beam anodes and ion-implanter hardware in vacuum or hydrogen. W (99.95% CP Tungsten) is the same commercially pure grade written as the mill certifies it, for drawings that call out purity rather than a trade name. EWP (WP) is the pure-tungsten TIG electrode: it forms a clean ball on AC and is the traditional choice for aluminum and magnesium welding, though lanthanated and ceriated electrodes now outlast it.
Which grade of pure tungsten is the strongest?
EWP (WP) has the highest yield strength in the series at 750 MPa; W (99.95% CP Tungsten) follows at 750 MPa. Values are for each grade's default condition.
Which grade of pure tungsten is easiest to machine?
W (99.95% CP Tungsten) (machinability not recommended, 12/100), then EWP (WP) (10/100).
Why is pure tungsten brittle when heavy alloy is not?
Body-centred-cubic tungsten has a ductile-to-brittle transition well above room temperature, and grain-boundary impurities and recrystallization push it higher still. Tungsten heavy alloys sinter the tungsten grains in a ductile nickel-iron binder that carries the strain, so WHA-90 bends and threads like steel at 17 g/cm³. If the part is not going above about 1,000 °C and does not need to be a pure surface, the heavy alloy is almost always the better engineering choice.
How hot can pure tungsten run?
In vacuum or inert gas, to within a few hundred degrees of its 3,422 °C melting point — crucibles and elements operate at 2,000–2,500 °C routinely. In air it is limited to about 500 °C, above which the oxide grows fast and becomes volatile near 1,000 °C. Recrystallization begins around 1,200–1,400 °C and embrittles the metal on cooling, which is why hot parts are designed never to be flexed cold again.