Tungsten carbide

What tooling is actually made of is cemented carbide: tungsten carbide grains glued together by 6-15% cobalt, and the cobalt content is the whole design variable — less cobalt gives more hardness and more brittleness. That binder also means no melting point can honestly be quoted for it. Pure WC melts at 2870 °C, but a cemented grade starts losing the cobalt from around 1300 °C and is finished as a tool long before either. Its stiffness of 600 GPa, three times steel's, is why carbide boring bars can reach further without chattering.

Properties

Density

14,900 kg/m³ (13,900–15,600) — 14.90 g/cm³

Tensile strength

800–1500 MPa

Young's modulus

600 GPa

Thermal conductivity

85 W/(m·K)

Hardness

9 Mohs

Thermal expansion

5.2 µm/(m·K)

Floats in water

No

Magnetic

No

What it is used for

• Milling, turning and drilling tool tips
• Masonry and rock drill bits
• Wear parts, dies and nozzles
• Wedding rings and watch cases

How it compares

Does it rust?

Tungsten carbide contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

Is it magnetic?

Tungsten carbide is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.