Tungsten needle is one of the main products made of the material of tungsten. Therefore, it owns the physical and chemical properties, which have been the unique characters of tungsten needle differ from needles made of other metals.
Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F) and the highest tensile strength. Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons. Alloying small quantities of tungsten with steel greatly increases its toughness. Therefore, the tungsten needle has the same physical property as pure tungsten material.
As to the chemical property of tungsten needle, can also be analyzed from the material of tungsten, which is oxidization resistance, corrosion resistance, abrasion resistance, and high temperature resistance. This has been the reason for tungsten needle can be store for long with unchangeable quality.