OK6/BK6 VK6-M
Grade
GOST OK6/BK6 (ОК6/БК6) · GB YG6 · ISO K10
VK6-M = вК6-М
Fine-grain version: higher hardness and edge sharpness for finishing hardened cast iron, non-ferrous alloys, plastics and precision dies; slightly lower toughness.
Values for the VK6-M condition
Other OK6/BK6 tempers and conditions
OK6/BK6 is listed in 4 conditions; see the grade overview at OK6/BK6.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
VK6Default ВК6 | Standard medium-grain WC-6Co: best all-round balance of hardness and toughness for cast-iron turning/milling and general wear parts. | — | 1,200 | 0 | 1,580 HV | 80 W/m·K |
ВК6-В | Coarse-grain version for interrupted cuts, rough machining and impact-loaded mining/percussion inserts where toughness matters more than hardness. | — | 1,300 | 0 | 1,400 HV | 85 W/m·K |
VK6-MThis page ВК6-М | Fine-grain version: higher hardness and edge sharpness for finishing hardened cast iron, non-ferrous alloys, plastics and precision dies; slightly lower toughness. | — | — | — | 1,680 HV | 75 W/m·K |
ВК6-ОМ | Ultrafine (with Cr/Ta grain-growth inhibitors) for micro-drills, PCB tooling and fine finishing of heat-resistant and hardened materials; highest hardness, lowest transverse rupture strength. | — | — | — | 1,780 HV | 70 W/m·K |
What is OK6/BK6 VK6-M?
OK6/BK6 VK6-M is OK6/BK6 in the VK6-M grade — fine-grain version: higher hardness and edge sharpness for finishing hardened cast iron, non-ferrous alloys, plastics and precision dies; slightly lower toughness. OK6/BK6 VK6-M has a tensile strength of 1,200 MPa (174 ksi), stronger than 94% of ceramic grades. Elongation at break is 0% and the elastic modulus is 635 GPa (92.1 Msi). OK6/BK6 VK6-M has a density of 14.9 g/cm³ (0.538 lb/in³), heavier than 96% of ceramic grades. It melts at 1,320°C (2,408 °F). VK6 is the default condition FabDigit quotes; VK6-M is available on request or by drawing note.
Advantages
- Stiff — 635 GPa (92.1 Msi), better than 97% of ceramic grades
- Polishes to a fine finish — 95/100, better than 97% of ceramic grades
- Tough — resists crack growth — 8.8 MPa·√m (8.01 ksi·√in), better than 82% of ceramic grades
Limitations
- Heavy — 14.9 g/cm³ (0.538 lb/in³), worse than 96% of ceramic grades
- High embodied carbon — 30 kg CO₂/kg, worse than 91% of ceramic grades
- Needs corrosion protection — 55/100, worse than 77% of ceramic grades
OK6/BK6 VK6-M properties
Typical room-temperature values for OK6/BK6 VK6-M; 10 are specific to this condition. Other listed values are OK6/BK6 reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
OK6/BK6 VK6-M has a density of 14.9 g/cm³ (0.538 lb/in³), heavier than 96% of ceramic grades. It melts at 1,320°C (2,408 °F).
Mechanical13
OK6/BK6 VK6-M has a tensile strength of 1,200 MPa (174 ksi), stronger than 94% of ceramic grades. Elongation at break is 0% and the elastic modulus is 635 GPa (92.1 Msi).
Thermal5
OK6/BK6 VK6-M is rated for continuous service to 600°C (1,112 °F). It conducts heat at 75 W/m·K (43.3 BTU/hr·ft·°F), better than 73% of ceramic grades. Thermal expansion is 4.8 µm/m·K (2.67 µin/in·°F).
Electrical2
OK6/BK6 VK6-M has an electrical resistivity of 2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 77% of ceramic grades.
Sustainability4
Producing a kilogram of OK6/BK6 VK6-M takes about 400 MJ of energy and emits 30 kg of CO₂ — more than 88% of ceramic grades. Typical recycled content is 30%.
Manufacturability3
OK6/BK6 VK6-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 OK6/BK6 VK6-M
Is OK6/BK6 easy to machine?
Only diamond grinding, wire/sinker EDM, laser or ultrasonic machining after sintering; green-state pressing/blank machining is the economical route for complex shapes.
Can OK6/BK6 be welded?
Not fusion weldable — join by vacuum/induction brazing with Ag-Cu-Ti or Cu-Mn filler at 700–900 °C, using a ductile Cu interlayer to absorb the CTE mismatch with steel.
Can OK6/BK6 be formed, bent or molded?
Made by wet-milling WC+Co powder, pressing/extrusion or CIP of the green body, then vacuum liquid-phase sintering or sinter-HIP at ~1420 °C with ~18–22% linear shrinkage.
What surface finishes work on OK6/BK6?
Diamond lapping/polishing to mirror finish; PVD TiN/TiAlN or CVD coating is common — surface should be micro-blasted and Co-etched before coating; electroplating is rarely used.
OK6/BK6 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 | 5.7 – 6.3 | 6 |
| C (free/total control)carbon balanced to avoid eta phase or free graphite | — | — |
| Cr3C2/TaC (inhibitor, ВК6-М/ОМ only)grain-growth inhibitor in fine/ultrafine variants | 0.2 – 1.5 | 0.6 |
| Fe+Ni+other impurities | ≤ 0.5 | 0.2 |
| WCtungsten carbide hard phase, balance ~94% | balance | — |
OK6/BK6 VK6-M — frequently asked
What is OK6/BK6 VK6-M used for?
OK6/BK6 VK6-M is typically used for cast iron machining, non-ferrous machining and general tooling. In short: standard CIS WC-6%Co grade; cast iron and non-ferrous cutting; high modulus, 630 GPa.
What is the tensile strength of OK6/BK6 VK6-M?
OK6/BK6 VK6-M has a typical tensile strength of 1,200 MPa (174 ksi) — stronger than 94% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is OK6/BK6 VK6-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 after sintering; green-state pressing/blank machining is the economical route for complex shapes.
Can OK6/BK6 VK6-M be welded?
Not fusion weldable — join by vacuum/induction brazing with Ag-Cu-Ti or Cu-Mn filler at 700–900 °C, using a ductile Cu interlayer to absorb the CTE mismatch with steel.
What surface finishes work on OK6/BK6 VK6-M?
Diamond lapping/polishing to mirror finish; PVD TiN/TiAlN or CVD coating is common — surface should be micro-blasted and Co-etched before coating; electroplating is rarely used.
Can OK6/BK6 VK6-M be formed, bent or molded?
Made by wet-milling WC+Co powder, pressing/extrusion or CIP of the green body, then vacuum liquid-phase sintering or sinter-HIP at ~1420 °C with ~18–22% linear shrinkage.
What is the maximum service temperature of OK6/BK6 VK6-M?
OK6/BK6 VK6-M is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ГОСТ 3882-74 Сплавы твёрдые спечённые. Марки — Gosstandart / Rosstandart (1974)
- ISO 513 Classification and application of hard cutting materials — ISO (2012)
- ASM Handbook Vol. 2 — Properties of Cemented Carbides — ASM International (1990)
- Cemented carbide grade datasheets (WC-6Co, K10/K20 class) — Zhuzhou Cemented Carbide / Sandvik Hard Materials (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.