Oct 30, 2020
Tungsten is a rare metal and an important strategic material. It was called "heavy stone" in ancient times. It was named by the Spanish De Purya in 1783. The content of tungsten in the earth's crust is 0.001%. There are 20 tungsten-containing minerals that have been discovered. Tungsten deposits are generally formed with the activity of granitic magma. After smelting, tungsten is a silver-white shiny metal with extremely high melting point and high hardness. Tungsten is a rare and high melting point metal, belonging to the VIB group of the sixth period (the longest period) of the periodic table. Tungsten is a silver-white metal that looks like steel. Tungsten has a high melting point, a very low vapor pressure, and a low evaporation rate. The chemical properties of tungsten are very stable. It does not react with air and water at room temperature, and is insoluble in hydrochloric acid, sulfuric acid, nitric acid and alkaline solutions. It is soluble in aqua regia and a mixture of nitric acid and hydrofluoric acid. It can be combined with chlorine, bromine, iodine, carbon, nitrogen, sulfur, etc. at high temperature, but not with hydrogenation.
Tungsten is mostly used in the production of special steel. Tungsten has tungsten rods, tungsten plates and other products. The widely used high-speed steel contains 9%-24% tungsten, 3.8%-4.6% chromium, 1%-5% vanadium, and 4%-7% cobalt. , 0.7%-1.5% carbon. The characteristic of high-speed steel is that it can be automatically quenched at a high tempering temperature (700-800℃) in the air. Therefore, it maintains high hardness and wear resistance until 600-650℃. Tungsten steel in alloy tool steel contains 0.8%-1.2% tungsten; chromium tungsten silicon steel contains 2%-2.7% tungsten; chromium tungsten steel contains 2%-9% tungsten; chromium tungsten manganese steel contains 0.5%-1.6% tungsten. Tungsten-containing steel is used to manufacture various tools: such as drills, milling cutters, drawing dies, female and male dies, air support tools and other parts. Tungsten magnet steel is a permanent magnet steel containing 5.2%-6.2% tungsten, 0.68%-0.78% carbon, and 0.3%-0.5% chromium. Tungsten-cobalt magnetic steel contains 11.5%-14.5% tungsten, 5.5%-6.5% molybdenum, 11.5%-12.5% cobalt hard magnetic materials. They have high magnetization and coercivity.
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