The thinnest sheets, commonly referred to as tungsten foils, can be as thin as 0.001 inches. More substantial sheets are available in thicknesses up to 5 inches.
Tungsten is a hard, heavy and rare metal found naturally in the earth’s crust. It was first identified as an element in 1781 and later as a metal in 1783. Mined tungsten ore is ground into a fine powder, at which point it is considered pure tungsten metal. The powder is typically molded into a bar shape, which can then be cold or hot-rolled into flat sheets, i.e. tungsten sheets. This production process also involves annealing, which is the heating and cooling process that strengthens the tungsten by removing any internal stresses.
This process is done by a vacuum annealing furnace. Further equipment used when processing tungsten for tungsten sheets include the following: a four-high cold mill, a straightener, hydraulic plate shears, a water jet, a wire cutting machine and a flat-stone mill. Tungsten sheets can have a variety of finishes, but the metal commonly has a similar appearance to that of steel.
Tungsten sheets, as well as other forms of tungsten, are valued because of their high tolerance to heat and corrosion resistance, consequently making them useful for many different industries, including the construction, engineering and medical industries. It is also used in the military. Commonly, tungsten is combined with other metallic elements, as to provide greater strength and resistance to wear-and-tear; these are called tungsten sheet alloys. Alloying tungsten with steel is a common example of this.
Tungsten sheet alloys are used for things such as radiation sheets, light bulb components, packaging materials, cables, shipbuilding, electro-vacuum industries, metallurgical machinery and electronics. Conversely, high purity tungsten sheets are also available, though not commonly supplied due to their brittle and hard condition; these contain highly pure tungsten and are therefore very characteristic of its original state. Because pure tungsten is highly conductive to electricity, highly pure tungsten sheets are used mainly in electrical applications.