2014 Annual Report on Tungsten Market
2015-07-16 14:16:55 【Print】
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As a rare metal, tungsten is an important strategic material
. World tungsten reserves are estimated to be 7 million tons, of which about 30% are in the form of scheelite minerals and 70% are in wolframite-group minerals . There are more than ten kinds of tungsten ores with wolframite and scheelite being the two major types in China . Pure tungsten is a steel-gray to tin-white metal . Very pure tungsten can be cut with a hacksaw (it is brittle and hard to work when pure) . The processing methods of tungsten include forging, drawing and extruding . Tungsten has the highest melting point (3415℃), lowest vapor pressure of all metals and highest tensile strength at the temperature of 1650°C . It has excellent corrosion resistance and is attacked only slightly by most mineral acids . The metal forms a protective oxide layer when exposed to air but can be oxidized at high temperature . The toughness of steel can be greatly increased when it is alloyed with small quantities of tungsten.