OK3/BK3 VK3-M
Grade
GOST OK3/BK3 (ОК3/БК3) · GB YG3 · ISO K01
VK3-M = 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.
Values for the VK3-M condition
Other OK3/BK3 tempers and conditions
OK3/BK3 is listed in 2 conditions; see the grade overview at OK3/BK3.
- VK3
- VK3-M
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 |
VK3-MThis page 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 VK3-M?
OK3/BK3 VK3-M is OK3/BK3 in the VK3-M grade — 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. OK3/BK3 VK3-M 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 655 GPa (95 Msi). OK3/BK3 VK3-M 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). VK3 is the default condition FabDigit quotes; VK3-M is available on request or by drawing note.
Advantages
- Stiff — 655 GPa (95 Msi), better than 99% of ceramic grades
- Polishes to a fine finish — 93/100, better than 95% of ceramic grades
- Tough — resists crack growth — 7.5 MPa·√m (6.83 ksi·√in), better than 76% of ceramic grades
- Conducts heat well — 78 W/m·K (45.1 BTU/hr·ft·°F), better than 75% 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 VK3-M properties
Typical room-temperature values for OK3/BK3 VK3-M; 10 are specific to this condition. Other listed values are OK3/BK3 reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
OK3/BK3 VK3-M 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 VK3-M 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 655 GPa (95 Msi).
Thermal5
OK3/BK3 VK3-M is rated for continuous service to 800°C (1,472 °F). It conducts heat at 78 W/m·K (45.1 BTU/hr·ft·°F), better than 75% of ceramic grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical1
OK3/BK3 VK3-M 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 VK3-M 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 VK3-M's machinability is not recommended (3/100, worse than 95% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with OK3/BK3 VK3-M
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.
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.
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 | — |
OK3/BK3 VK3-M — frequently asked
What is OK3/BK3 VK3-M used for?
OK3/BK3 VK3-M 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 VK3-M?
OK3/BK3 VK3-M 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 VK3-M easy to machine?
Not especially — machinability is rated not recommended (3/100, worse than 95% 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 VK3-M 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 VK3-M?
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 VK3-M 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 VK3-M?
OK3/BK3 VK3-M 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.