Tungsten grades / Tungsten carbide
Tungsten Carbide
Not a tungsten alloy in the metallurgical sense. A sintered cermet, shaped by grinding and EDM rather than cut on a mill or lathe.
Tungsten carbide, written WC-Co, is a composite of tungsten carbide grains bonded with cobalt. It shares the name "tungsten" with the other three grades on this site but not the composition or the process: heavy alloy and pure tungsten are metals that turn and mill, carbide is a ceramic-metal composite that is ground and EDM cut instead. If your part is specified as carbide, expect a very different quote and process from a heavy alloy or pure tungsten part of similar size.
| Property | Typical value |
|---|---|
| Density | 14.5 to 15.6 g/cm³, typical |
| Hardness | Roughly 85 to 93 HRA, typical |
| Magnetic behavior | Mildly magnetic, from the cobalt binder |
| Typical tolerance | ±0.005 mm or better by grinding |
Typical density
Tungsten carbide runs 14.5 to 15.6 g/cm³, typical, lower than either pure tungsten or heavy alloy despite the name. Density is not the reason carbide is specified; hardness and wear resistance are.
Hardness
Tungsten carbide typically runs 85 to 93 HRA, far above the HRC range used for heavy alloy and tool steel, and harder than almost any cutting tool material except diamond. This is the same hardness that makes carbide useful as a cutting tool material in the first place: a milling cutter cannot remove metal from a workpiece harder than itself, which is the direct reason sintered carbide is ground rather than milled.
Magnetic or non-magnetic
Tungsten carbide is mildly magnetic, not fully non-magnetic, because of the cobalt binder that holds the carbide grains together; cobalt itself is ferromagnetic. This is a small effect in most applications, but it is real, and it is why magnetic saturation measurement is actually used industrially as an indirect way to check a carbide grade's cobalt content. If a part must be strictly non-magnetic, carbide is not the grade to specify; tungsten heavy alloy in W-Ni-Cu, or pure tungsten, are the non-magnetic options on this site.
How it machines
Sintered tungsten carbide cannot be milled or turned in almost every case. The hardness that makes it useful as a cutting tool also makes it too hard for standard cutting tools to remove. Two approaches work around this: machining the part while it is still a soft, unsintered powder compact before the sintering step that hardens it, which works for simple geometry established early; or grinding and EDM after sintering, using diamond wheels harder than the sintered carbide, or wire and sinker EDM that erodes material electrically rather than by cutting. A drawing that calls for milled slots, pockets or holes on finished sintered carbide describes an operation most shops cannot perform as specified, and will usually come back proposing grinding, EDM, or a design change to machine the feature before sintering.
Typical achievable tolerance
±0.005 mm or better is achievable by grinding, typical, tighter than what milling and turning hold on the metallic grades. This precision is part of why carbide is chosen for gauges, dies and tooling where dimensional stability under wear matters as much as the initial tolerance.
A note on ASTM B777
ASTM B777 covers tungsten heavy alloy, a metal, not tungsten carbide, a cermet. It does not apply here. Carbide grades are specified by composition (such as WC-Co with a stated cobalt percentage) and hardness grade rather than by a B777 class.
Typical applications
- Cutting tool blanks and inserts
- Wear-resistant dies and punches
- Precision gauges and nozzles that must hold size under repeated wear
- Mining and drilling tool tips
Sources
Have a carbide part to source? Get matched with a shop that grinds and EDMs this grade.
Related: grinding tungsten carbide vs machining and pure tungsten vs heavy alloy vs carbide.