Tungsten is known for its extreme properties, including the highest melting point of all metals and a density comparable to gold. This steel-gray metal is used in industrial applications and in jewelry like wedding bands. Since metal detectors locate metals based on physical characteristics, determining if tungsten is detectable requires examining how these devices work and the metal’s specific electrical and magnetic profile.
How Metal Detectors Sense Materials
Metal detection relies on electromagnetic induction to identify metallic objects. The detector’s search coil generates a primary magnetic field by passing an alternating electrical current through its windings. This field extends outward and penetrates the scanned area.
When this magnetic field encounters a conductive metal object, it induces small, circular electrical currents known as Eddy currents. These Eddy currents generate their own secondary magnetic field, which the detector’s receiver coil picks up. The detector analyzes the strength and phase of this secondary field to determine the metal’s presence and characteristics. Detection therefore depends heavily on a material’s electrical conductivity.
Tungsten’s Electrical and Magnetic Profile
Tungsten’s detectability is determined by its electrical conductivity and magnetic characteristics. Pure tungsten is non-ferromagnetic, meaning it is not strongly attracted to magnets like iron or nickel, and does not generate a strong magnetic response signal. Although classified as paramagnetic, its magnetic susceptibility is extremely low, rendering it practically non-magnetic.
Tungsten is an electrical conductor, allowing for the creation of Eddy currents, but its conductivity is moderate compared to other common metals. At room temperature, tungsten’s electrical conductivity is approximately 1.8 x 10^7 Siemens per meter (S/m). Highly detectable metals like copper and silver have significantly higher conductivities, around 6.0 x 10^7 S/m. This lower conductivity means that the Eddy currents generated in a tungsten object will be weaker, resulting in a less pronounced secondary magnetic field.
Detection Outcomes in Real-World Use
Tungsten can be detected because it is conductive, but the signal is often weaker and more variable than that produced by highly conductive metals. Its moderate conductivity makes it a challenging target for less sensitive equipment. Furthermore, consumer items like rings are often made from tungsten carbide alloys, which may contain other metals that affect the overall electrical response.
The ability to detect tungsten depends on the size of the object and the sensitivity of the detector. A large, dense tungsten ingot will trigger any detector due to its mass. However, a small tungsten ring may only be picked up by high-sensitivity or specialized detectors. Hobbyist detectors often assign tungsten a lower target identification number (e.g., 63 or 76) compared to highly conductive copper or silver objects. The successful recovery of lost tungsten rings confirms the metal is detectable by modern technology.