Tungsten Bar and Tungsten Wire

At present, tungsten filament is mainly used as electric light source of electric incandescent lamp, halogen tungsten lamps and others. When using as a luminous body of the filament lamp, a small amount of potassium, silicon and aluminum oxides should be added during the smelting process. This kind of wolfram filament is also known as doped tungsten wire and 218 wolfram wire or anti-drooped tungsten filament. Uniformity condition of density of tungsten bar plays an important role in the quality of tungsten product. The number, size and distributing condition of holes of wolfram bar not only have a greater impact on its high-temperature performance, but also affect the mechanical properties.

Processing tungsten round bars and square bars made from the same batch of tungsten powder raw material. After stretching them to 500W finished wire, using Japan or West Germany crack flaw detectors to detect 50000m wolfram filament respectively. By the force of contrast, it can be found that, the total length of the crack of tungsten wire prepared by round tungsten bar is about 0.98% to 1.20% of. On the other hand, for the same specification of tungsten square bar, crack accounts for 4.21% ~ 58.82% of the entire length of wolfram filament. Obviously, the crack of tungsten filament made by tungsten round bar is much smaller than square bar. Tungsten is widely used as refractory metals. In wire form, wolfram wire is essential for the production of lighting products and other goods where its high temperature properties are of use. Its properties are a melting point of 3410° C, a low coefficient of thermal expansion and low vapor pressure at elevated temperatures along with good electrical and thermal conductivity.

From the perspective of wire-wound performance, under the same conditions, the wire-wound performance of wolfram filament prepared by round bar is better than the square one. According to the spiral resilience, we can see that the helical filament of the tungsten round wire would not crack in the stretching process, and the distance of the pitch is relatively equal. Under the same situation, square spiral filaments have the flerry phenomenon.

All in all, any non-uniformity processing of wolfram bar will cause the deformation of tungsten material, leading to its internal organization become non-uniformity, causing breakage of the inner wall of wire, especially at the junction of uneven tissue, which is more easily to have a crack.

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