made of tungsten wire drawing process

The earliest for the production of incandescent tungsten filament. 1909 U.S. Kuli Ji (WDCoolidge) using tungsten powder pressing, remelting, swaging, made of tungsten wire drawing process, from tungsten production has been growing rapidly. 1913 Langmuir (I.Langmuir) and Rogers (W.Rogers) found thorium tungsten wire (also known as thorium tungsten filament) electron emission performance than pure tungsten, start using thorium tungsten wire, is still widely used. 1922 developed with excellent anti-sagging properties of tungsten wire (called doping does not sag tungsten or tungsten), which is the study of tungsten significant progress. Does not sag tungsten filament is excellent and widely used cathode material. 50 to 60 years, for tungsten alloy conducted extensive exploration and research, hopes to develop in 1930 ~ 2760 ℃ working tungsten alloy, used for making high-temperature aerospace industry components. Tungsten-rhenium alloy which more research. tungsten carbide inserts smelting and processing forming technology also carried out research, using consumable arc and electron beam melting tungsten ingot obtained and processed by extrusion and plastic products made from certain; but smelt ingots coarse grains, poor plasticity , processing difficulties, finished product rate, thereby melting - plastic processing technology does not become the main means of production. In addition to chemical vapor deposition (CVD method), and plasma spraying can produce very few products, made of tungsten powder metallurgy products are still the primary means.In the 1950s, China has been able to produce tungsten material. 1960 tungsten smelting, metallurgy and processing carried out research, is now able to produce plate, sheet, foil, bar, pipe, wire and other shaped pieces. Tungsten materials using high temperature, only using the solid solution strengthening methods to improve the high temperature strength of tungsten little effect. However, in the solution based on the further strengthening dispersion (or precipitation) hardening, to greatly improve the high temperature strength, and precipitated with ThO2 HfC particle dispersion strengthening effect is best. At 1900 ℃ or so W-Hf-C system and the W-ThO2 alloys have a high-temperature strength and creep strength. Used below the recrystallization temperature of the tungsten alloy, taking temperature hardening methods, to produce strain hardening is an effective way to strengthen. Such as fine tungsten wire with high tensile strength, deformation rate of 99.999% total processing a diameter of 0.015 mm thin tungsten wire, room temperature tensile strength of up to 438 kg / mm; in refractory metals, tungsten and tungsten alloy plastic - brittle transition temperature maximum. Sintering and melting of the plastic material of polycrystalline tungsten - brittle transition temperature is about 150 ~ 450 ℃ between, resulting in difficulties in processing and use, and the single crystal of tungsten is below room temperature. Tungsten material in the interstitial impurities, microstructure and alloy elements, and plastic processing and surface state, the plastic timber tungsten - brittle transition temperature has a significant impact.