Tungsten is a kind of rare metal, and it's also the important strategic materials, it was known as "scheelite" in the ancient times. It was named by the Spaniard Depp Aria in 1783. The content of tungsten is 0.001% in the crust. There are 20 kinds of the tungsten minerals have been found. Tungsten deposits are usually formed with the granitic magmatic activities. After smelting, the tungsten is silver white lustrous metal with high melting point, high hardness. Tungsten is a rare metal with high melting point, which belongs to the sixth period (the second long period ) VIB group in the periodic table of the elements. Tungsten is a silvery white metal, and its shape seems like steel. Tungsten has the high melting point, low vapor pressure and the little evaporation rate.

The chemical properties of tungsten is very stable. In the normal temperature, there isn't reaction with the air and water, and it doesn't dissolve in the hydroelectric acid, sulfuric acid, nitric acid and alkali solution. Soluble in aqua regia and mixed solution of nitric acid and hydroelectric acid. In high temperature, it can be combined with chlorine, bromine, iodine, carbon, nitrogen, sulfur except for the hydrogen, Tungsten are used mostly for the production of special steel. The widely used high speed steel  contains 9% -- 24% tungsten, 3.8% -- 4.6% chromium, 1% -- 5% vanadium, 4% -- 7% cobalt, 0.7% -- 1.5% of carbon. The characteristic of high speed steel is that it can automatically quench with high hardening tempering temperature (700 -- 800 ℃) in the air, therefore, it can also keep high hardness and wear resistance until 600 - 650 ℃

Tungsten steel in alloy tool steel contains tungsten of 0.8% -- 1.2%, chromium tungsten silicon steel contains tungsten of 2% -- 2.7%, chromium tungsten steel contains tungsten of 2% -- 9%, chromium tungsten manganese steel contains  tungsten of 0.5% -- 1.6%. The steel of containing tungsten used in the manufacture of various tools, such as drill, cutter, wire drawing die, pneumatic tool parts. Tungsten steel is a permanent magnet steel containing tungsten of 5.2% -- 6.2%, carbon of 0.68% -- 0.78% and Cr of 0.3% -- 0.5%. Cobalt tungsten magnet steel is hard magnetic materials of containing tungsten of 11.5% -- 14.5%, molybdenum of 5.5%-- 6.5% and cobalt of 11.5% -- 12.5%. They have high magnetization and coercive force.