FAQ - Service- Und Qualitätsmarktführer Für Wolfram

General

What is the density of tungsten?

With 19.25g / cm³ the density of tungsten is about 2.5 times higher than that of steel (~7.85 g / cm³)

What is the hardness of tungsten (minimum)?

Tungsten has a hardness of about 350 HV10, although it also depends very much on the deformation and the process temperatures.

What is the crystal structure of tungsten?

– Automotive (cubic – face-centred structure)
– KRZ (cubic – body-centred structure)
– Hexagonal (hexagonal structure)
Tungsten has the same lattice structure as ferritic steel. Cubic body-centred metals have a transition temperature between the brittle and ductile phase.
For ferrite this is ~20°C, for tungsten it can be 200-400°C, which is why tungsten is brittle at room temperature.

What is the melting temperature of tungsten?

3420°C, the highest of all pure metals.

What do you call the reaction of tungsten in combination with oxygen?

Sintering, oxidation, crystallisation
It can form various tungsten oxides and non-stoichiometric mixed oxides with characteristic colours: WO2 bluish – WO3 yellowish.

At what temperature is the reaction with oxygen striking?

50°C, 200°C, 400°C

At what temperature does the WO3 (oxide layer) evaporate?

750°C, 850°C, 1000°C
The yellowish oxide decomposes the surface and is harmful in most cases.

TRIAMET® is manufactured with the following sintering methods:

Direct sintering and indirect sintering.
In indirect sintering, in contrast to direct sintering of pure tungsten, the microstructure forms via liquid phase sintering.

A “green blank” is …

… a compressed powder (not sintered). The pressing can be done with and without the addition of organic binder.

TRIAMET (Tungsten-based heavy alloy)

Which elements make up the tungsten-based heavy alloys (TRIAMET® G)?

Element 1: Tungsten
Element 2: Nickel
Element 3: Iron

Tungsten forms a characteristic microstructure with a globular structure and a binder phase of iron and nickel.

What is the basis of the tungsten-based heavy alloys (TRIAMET® S)?

Element 1: Tungsten
Element 2: Nickel
Element 3: Copper

Our S-material is used wherever the material should not be magnetisable.

The direct sintering process is the following process:

Placing the pressed green blank into a sintering furnace.
Clamping the pressed green blank between two electrical contacts.
Pure tungsten is sintered at about 80% of the melting temperature [K]. Such temperatures can be achieved most easily by electrical resistance heating.

Tensile strength of TRIAMET® G17B?

750 – 1000 N/mm²
For comparison: V2A steel (1.4301) usually has a tensile strength between 500-700 N/mm²

What is the typical elongation at break of TRIAMET® G17B?

10 – 30%
It is the tungsten product with one of the highest strains.

What are the main areas of application for TRIAMET®?

Material properties such as high density, low affinity to aluminium and copper, high bending stiffness and easy machinability are used for:

– Shielding for nuclear medicine
– Balance weights for engine construction
– Tool holders
– Foundry moulds
– Others

Which material properties are influenced by porosity in TRIAMET®?

Depending on the size of the porosity, elongation at break and ductility are reduced.

What is the main difference between TRIAMET®G and TRIAMET®S?

TRIAMET®G is slightly ferromagnetic.
TRIAMET®S is non-magnetic (paramagnetic).

What is the typical hardness of TRIAMET®G 18?

290-340 HV10

What is the maximum application temperature of TRIAMET®G?

1300°C
However, we recommend not exceeding the application temperature of 1000°C.

What happens when an application temperature for TRIAMET®G of … is exceeded

… of 1300°C is exceeded?
The material loses strength.

And 1.440°C?
The binder phase melts.

TUNGSTIT® (WCu and WAg)

Which pseudo alloy shows higher corrosion resistance?

WCu and Wag

DOTIMET® (tungsten granulate)

How is tungsten granulate characterised in C and S analyses?

Tungsten granulate serves as accelerator material for determining the carbon and sulphur content. Often we use this granulate with a grain size between 0.5-2.0mm.

How is tungsten granulate characterised for mass balancing?

Bulk and tap density
Granulate for mass balancing has good damping properties, which can be advantageous in dynamic systems.