Tungsten is a metal that is grayish-white in appearance. It is solid at room temperature, and according to the associates at Tungsten.com, tungsten has the highest melting point of any metal (6170 degrees Fahrenheit). This metal has a high tensile strength and is very resistant to corrosion.
Tungsten is most widely used in the construction of light bulb filaments because it has a high tolerance for heat. Tungsten filaments can burn at temperatures upwards of 4,600 F.
Many types of light bulbs employ tungsten as a filament material. Incandescent bulbs as well as halogen bulbs use tungsten filaments.
At such high temperatures, tungsten evaporates, and eventually a tungsten filament will become so degraded that it will break or melt.
Halogen light bulbs contain traces of a halogen. According to The Great Internet Light Bulb Book, the halogen in a light bulb will actually deposit evaporated tungsten molecules back onto the tungsten filament. This “halogen cycle” is known to increase the life of certain light bulbs such as halogen bulbs.