Cemented Tungsten Carbide
Cemented carbide is tungsten-carbide grains, typically 0.5–5 µm, sintered in a cobalt binder — a ceramic-metal composite rather than an alloy. The cobalt content sets the balance: WC-6Co is about 91–92 HRA (roughly 1,600 HV) with a transverse rupture strength near 2,000 MPa; WC-12Co drops to 88–89 HRA and gains toughness, with rupture strength above 3,000 MPa. Density is 14–15 g/cm³, the modulus 550–620 GPa, and the hardness holds to about 500 °C, beyond which oxidation and cobalt softening take over.
Popular cemented carbide grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| WC-6Co | 1,700 | 1,300 | 14.9 | Not recommended | Not recommended | Cutting inserts, drawing dies, seal faces |
| WC-10Co | 1,500 | 1,300 | 14.5 | Not recommended | Not recommended | General wear parts, nozzles, bushings |
| WC-12Co | 1,400 | 1,400 | 14.2 | Not recommended | Not recommended | Punches and dies that see impact |
Choose cemented carbide for
Cutting inserts, end mills, drills and reamers; wire-drawing, cold-heading, powder-compaction and stamping dies; punches, nozzles, seal rings, wear plates, bearing balls and rolls — any surface that must stay hard and dimensionally stable under abrasion, and any part where a grindable blank brazed into a steel body puts the hardness only where it is needed.
Look elsewhere when
The part sees bending or impact as its main load (a hardened tool steel such as D2 or S7 survives what carbide shatters under), it is a complex 3D shape that cannot be pressed and ground (WHA-90 machines conventionally), it runs above 500 °C in air (a ceramic or Stellite 6), or a coated steel tool is good enough — carbide costs several times as much as tool steel and cannot be sharpened on the shop grinder.
Loading the library…
Cemented carbide by application
- Cutting tools
- WC-6Co in fine or submicron grain for inserts, end mills and drills, usually PVD- or CVD-coated; TiC and TaC additions for steel turning where crater wear governs.
- Forming and drawing dies
- WC-6Co for wire-drawing dies and steady-load forming; WC-10Co for compaction and extrusion dies; WC-12Co for cold-heading and stamping punches that take shock.
- Wear and seal parts
- WC-10Co for nozzles, seal rings, bushings, flow-control trim and wear pads; WC-6Co where the mating surface is also carbide and finish matters most.
Working with cemented carbide
- Grinding and EDM
- Carbide is not cut, it is shaped: pressed and sintered to a blank about 20 % oversize, then diamond-ground, wire- or sinker-EDMed and lapped. Tolerances of ±0.002 mm and mirror finishes are routine on grindable geometry; EDM leaves a heat-affected recast layer that is ground or polished away on critical edges.
- Brazing to steel
- Silver-based fillers with nickel or manganese wet the carbide; a copper or trimetal shim absorbs the expansion mismatch (carbide 5–6 ppm/K, steel 12 ppm/K) on joints longer than about 25 mm. Heat evenly and cool slowly, or the carbide cracks as the steel contracts around it.
- Design rules
- Keep sections uniform, radius every internal corner, avoid threads and thin flanges, and load the carbide in compression. Cobalt leaches in some coolants, which weakens the surface; specify a coolant rated for carbide when the part is a wear component in a wet system.
Other tungsten alloy series
Cemented Tungsten Carbide — frequently asked
What is cemented carbide?
Cemented carbide is tungsten-carbide grains, typically 0.5–5 µm, sintered in a cobalt binder — a ceramic-metal composite rather than an alloy. The cobalt content sets the balance: WC-6Co is about 91–92 HRA (roughly 1,600 HV) with a transverse rupture strength near 2,000 MPa; WC-12Co drops to 88–89 HRA and gains toughness, with rupture strength above 3,000 MPa. Density is 14–15 g/cm³, the modulus 550–620 GPa, and the hardness holds to about 500 °C, beyond which oxidation and cobalt softening take over.
Which grade of cemented carbide should I use?
WC-6Co for cutting edges and steady sliding wear — inserts, end mills, drawing dies, wear pads, seal faces — where hardness matters more than shock resistance. WC-10Co as the general-purpose wear grade for nozzles, bushings, valve trim and forming dies. WC-12Co for punches, cold-heading dies, mining picks and anything that sees impact, where a 6 % grade would chip. Finer grain size raises hardness at the same cobalt content; grades with added TiC and TaC resist cratering when steel chips slide over them.
Which grade of cemented carbide is the strongest?
WC-6Co has the highest yield strength in the series at 1,700 MPa; WC-10Co follows at 1,500 MPa. Values are for each grade's default condition.
Which grade of cemented carbide is easiest to machine?
WC-6Co (machinability not recommended, 3/100), then WC-10Co (3/100).
How hard is tungsten carbide compared with hardened steel?
A 60 HRC tool steel is about 700 HV; WC-6Co is about 1,600 HV and WC-12Co about 1,300 HV, and the carbide keeps that hardness to 500 °C where steel begins to temper back. Only diamond and cubic boron nitride are harder. The trade-off is toughness — even WC-12Co has a fracture toughness a third to a half of a good tool steel — so carbide is used as a hard skin or insert on a steel body.
Why does carbide chip, and what stops it?
Low fracture toughness: a sharp edge, a tensile bending load or a thermal shock starts a crack that nothing arrests. Move to a higher cobalt grade (WC-10Co or WC-12Co), hone the edge, add a radius, preload the part in compression by shrink-fitting it into a steel sleeve, and avoid intermittent coolant on a hot edge. A tougher grade will wear a little faster but will still be in one piece.