Tungsten Bar and Tungsten Rod

Wolfram has the highest melting point of all metals and is therefore also suitable for very high-temperature applications. It is also characterized by a uniquely low coefficient of thermal expansion and a very high level of dimensional stability. Tungsten rod is a kind of metal rod made of metal tungsten, at high temperatures, as a high melting point and low coefficient of thermal expansion material, so it is now widely used for support line, lead-in wire, printer pin, various electrodes and quartz furnace, filament, high-speed tools, automotive products and other industrial fields. Better wear resistance, higher toughness, better deformation and fracture resistance, results in a long life and good size accuracy. Except formed by metal tungsten powder, wolfram rod can also made through the process of the manufacturing of tungsten bar.

Tungsten bar can be divided into wolfram round bars and square bars, during the processing of swaging for tungsten rod, the obtained finished products would have some differences. When both of them are processing to 8mm in diameter, from the view of the sectional of metallurgical structure, the four corners of tungsten square bar are easy to form recrystallized structure under the conditions of processing temperature. If the follow-up process shall not be treated properly, it will result in the interior tissue of the wolfram rod is uneven, which is the main reason for defects and breaking of the following finished wolfram products. On contrary, after tungsten round bar is being stretched to 8mm in diameter, it still remains uniform tissue density. Nonuniform structure tends to cause internal defects of silk material, if uneven degree is very serious that it cannot be processed any more.

Observe hole distribution of this kind of metal rod after annealing, which can be used the scanning electron microscope, you will see the hole of the recrystallized structure correspond to four edges  are less, almost no orifice tube, but there are more holes in intermediate position of the wolfram rod. However, there are not exist recrystallized structure of the tungsten round bars, so its tissue distribution remains homogeneous state in follow-up processing. Internal tissue density distribution of tungsten bar has a great impact on the preparation of the following processes of tungsten rod and tungsten products. Therefore, the users should choose the right tungsten bars according to their own requirements.

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