Technical guide · 2026-08-14
Cobalt-Bonded Hardmetals
Cobalt-bonded hardmetals use a ductile cobalt binder around tungsten-carbide or related hard particles; carbide size, binder fraction, porosity and sintering route define grade behavior beyond nominal WC-Co chemistry.
01
Definition and boundary
Covers cemented-carbide composites; excludes bulk cobalt alloys and loose cobalt-containing powders sold without consolidation acceptance.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Carbides carry compressive wear loads.
Cobalt binder bridges cracks.
Grain size and binder fraction trade hardness against toughness.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| WC-6Co fine grain | Hardness-led cutting grade family. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| WC-10Co medium grain | Balanced wear/toughness family. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| WC-15Co coarse grain | Impact-tough hardmetal family. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
04
Properties and trade-offs
Hardness
Transverse-rupture strength
Porosity-sensitive fatigue
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Cutting inserts
- Mining buttons
- Wear nozzles and dies
Properties and trade-offs
- Match grain/binder to impact.
- Specify coating separately.
- Control recycled powder where critical.
07
Fabrication, durability and inspection
Control milling contamination.
Qualify pressing and sintering shrinkage.
Finish-grind with crack inspection.
08
Procurement checklist
- State carbide type, grain size and cobalt binder fraction.
- Define porosity class, eta phase and free carbon acceptance.
- Specify density, hardness, rupture test and lot traceability.
09
Standards, sources and review
Standards and designation context
- Applicable ASTM or ISO product scope
- Buyer drawing and service qualification
- Agreed inspection and certification plan