OK3/BK3
GOST OK3/BK3 (ОК3/БК3) · GB YG3 · ISO K01
ОК3/ БК3 (VK3) is a low-cobalt GOST straight WC-3%Co cemented carbide, the CIS counterpart of C4 and YG3, supplied in VK3 and fine-grain VK3-M conditions.
Reference datasheet — OK3/BK3 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the VK3 condition
OK3/BK3 tempers and conditions
OK3/BK3 is supplied in 2 conditions, soft to hard. VK3 is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
VK3Default ВК3 | Standard ВК3 for finish turning/boring of cast iron, non-ferrous metals and plastics at moderate speeds. | — | 1,100 | 0 | 1,500 HV | 85 W/m·K |
ВК3-М | Fine WC grain size (~1 µm) version — higher hardness and sharper, more durable cutting edges for precision finishing of hardened steel, cast iron and alloys; slightly lower toughness. | — | — | — | 1,700 HV | 78 W/m·K |
What is OK3/BK3?
ОК3/ БК3 (VK3) is a low-cobalt GOST straight WC-3%Co cemented carbide, the CIS counterpart of C4 and YG3, supplied in VK3 and fine-grain VK3-M conditions. The low binder fraction gives the highest hardness and wear resistance of the VK family, which is why it is used for precision finishing tools, gauges and small die inserts in rod, strip and insert form. Elastic modulus is 650 GPa, thermal conductivity 85 W/m·K and maximum service temperature about 800 °C. Impact and shock resistance are the lowest of the group, so avoid interrupted cuts and choose VK6 or VK8 where edge chipping is a risk. OK3/BK3 has a density of 15.15 g/cm³ (0.547 lb/in³), heavier than 99% of ceramic grades. It melts at 1,320°C (2,408 °F). OK3/BK3 has a tensile strength of 1,100 MPa (160 ksi), stronger than 88% of ceramic grades. Elongation at break is 0% and the elastic modulus is 650 GPa (94.3 Msi).
What is OK3/BK3 used for?
- precision finishing
- dies
- fine wear parts
Advantages
- Stiff — 650 GPa (94.3 Msi), better than 98% of ceramic grades
- Tough — resists crack growth — 8.5 MPa·√m (7.74 ksi·√in), better than 79% of ceramic grades
- Conducts heat well — 85 W/m·K (49.1 BTU/hr·ft·°F), better than 79% of ceramic grades
- Polishes to a fine finish — 90/100, better than 78% of ceramic grades
Limitations
- Heavy — 15.15 g/cm³ (0.547 lb/in³), worse than 99% of ceramic grades
- High embodied carbon — 25 kg CO₂/kg, worse than 78% of ceramic grades
- Needs corrosion protection — 55/100, worse than 77% of ceramic grades
OK3/BK3 properties
Typical room-temperature values for OK3/BK3-VK3; bars are the position among ceramic grades.
Physical3
OK3/BK3 has a density of 15.15 g/cm³ (0.547 lb/in³), heavier than 99% of ceramic grades. It melts at 1,320°C (2,408 °F).
Mechanical12
OK3/BK3 has a tensile strength of 1,100 MPa (160 ksi), stronger than 88% of ceramic grades. Elongation at break is 0% and the elastic modulus is 650 GPa (94.3 Msi).
Thermal5
OK3/BK3 is rated for continuous service to 800°C (1,472 °F). It conducts heat at 85 W/m·K (49.1 BTU/hr·ft·°F), better than 79% of ceramic grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical1
OK3/BK3 has an electrical resistivity of 1.9×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 77% of ceramic grades.
Sustainability4
Producing a kilogram of OK3/BK3 takes about 320 MJ of energy and emits 25 kg of CO₂ — more than 78% of ceramic grades. Typical recycled content is 30%.
Manufacturability3
OK3/BK3's machinability is not recommended (4/100, worse than 85% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. OK3/BK3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with OK3/BK3
Is OK3/BK3 easy to machine?
Only diamond grinding, wire/sinker EDM, laser or ultrasonic machining; green-state pressing/pre-sinter machining is the economical route to shape.
Can OK3/BK3 be welded?
Not fusion-weldable — join by vacuum/induction brazing with Ag-Cu-Ti or Cu-Mn filler below 900 °C, using ductile interlayers to absorb the CTE mismatch with steel.
Can OK3/BK3 be formed, bent or molded?
Formed by uniaxial/CIP pressing or extrusion of WC-Co powder with wax binder, then dewaxing and liquid-phase vacuum or Sinter-HIP sintering at 1400-1500 °C with ~18-22 % linear shrinkage.
OK3/BK3 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cobinder phase | 2.5 – 3.5 | 3 |
| othertrace grain-growth inhibitors (VC/Cr3C2) and impurities, mainly in the -М variant | 0 – 0.5 | 0.2 |
| WCtungsten carbide hard phase; total C ~5.8 wt% of WC | balance | — |
What surface finishes work on OK3/BK3?
Diamond wheel grinding then diamond lapping/polishing to mirror finish; PVD TiN/TiAlN or CVD coatings are common; blasting or edge honing controls edge micro-geometry.
Equivalent designations
Standards and trade names that resolve to OK3/BK3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- K01
- GB (China)
- YG3
- GOST
- ОК3/БК3
How much does OK3/BK3 cost?
OK3/BK3 is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
OK3/BK3 — frequently asked
What is OK3/BK3 used for?
OK3/BK3 is typically used for precision finishing, dies and fine wear parts. In short: hardest low-cobalt VK grade; precision finishing and dies; highest modulus, 650 GPa.
What is the tensile strength of OK3/BK3?
OK3/BK3 has a typical tensile strength of 1,100 MPa (160 ksi) — stronger than 88% of ceramic grades. Strength varies by condition: see the 2 listed tempers.
Is OK3/BK3 easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 85% of ceramic grades). Only diamond grinding, wire/sinker EDM, laser or ultrasonic machining; green-state pressing/pre-sinter machining is the economical route to shape.
Can OK3/BK3 be welded?
Not fusion-weldable — join by vacuum/induction brazing with Ag-Cu-Ti or Cu-Mn filler below 900 °C, using ductile interlayers to absorb the CTE mismatch with steel.
What surface finishes work on OK3/BK3?
Diamond wheel grinding then diamond lapping/polishing to mirror finish; PVD TiN/TiAlN or CVD coatings are common; blasting or edge honing controls edge micro-geometry.
Can OK3/BK3 be formed, bent or molded?
Formed by uniaxial/CIP pressing or extrusion of WC-Co powder with wax binder, then dewaxing and liquid-phase vacuum or Sinter-HIP sintering at 1400-1500 °C with ~18-22 % linear shrinkage.
What is the maximum service temperature of OK3/BK3?
OK3/BK3 is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does OK3/BK3 cost?
OK3/BK3 is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- GOST 3882-74 — Сплавы твердые спеченные. Марки — Gosstandart (1974)
- ISO 513 — Classification and application of hard cutting materials — ISO (2012)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Cemented Carbides) — ASM International (1990)
- Cemented carbide grade property tables (low-Co K-grades) — Sandvik Hard Materials / Zhuzhou Cemented Carbide (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.