Cobalt Chromium Alloy 6B
Hard and Wear-Resistant Alloy AMS 5894
A History and Education
The Haynes Stellite corporation was founded by Elwood Haynes, who originated the Stellite grade. Alloys 6 and 6B being the most commonly known to industry.
He was an American inventor who lived during the late 19th century and was also known for his work in the automotive industry. His Stellite bridged the gap between high speed steels and carbides. Stellite addressed the demands of industry in the 1920’s, 30’s and 40’s for improved cutting of the modern alloys, which were becoming more common in the workplace.
The company was later sold to Union Carbide, which eventually sold it in 1972 to the Deloro Stellite Company.
Other alloys that were born from Elwood’s inventions were Talonite, an alloy similar to Stellite, which has a unique combination of hardness, wear resistance and machinability and Vitallium, which is typically used for dental and medical implants.
Material Data Sheet
Alloy 6B is an extensively hot worked alloy within a group of cobalt-chromium ‘super-alloys’ consisting of complex carbides in an alloy matrix predominantly designed for high wear resistance and superior chemical and corrosion performance in hostile environments. The combination of Cobalt and Chromium also results in an extremely high melting point making it perfect for a range of intriguing applications from extreme cutting tools to hot section alloy coatings in gas turbines.
Cobalt Chromium alloys are non-magnetic and typically associated with high corrosion resistance and as with many alloys, they are adaptable and can be refined for a range of specific applications. Due to their incredibly hard material properties, Alloys 6 and 6B are inherently difficult and often expensive to machine, therefore some very precise casting and grinding methods are often employed.
| Element | Content % |
|---|---|
| Cobalt, Co | 67.0 |
| Chromium, Cr | 32.0 |
| Tungsten, W | 5.5 |
| Carbon, C | 1.4 |
| Iron, Fe | 0.03 |
| Nickel, Ni | 0.03 |
| Mangangese, Mn | 0.02 |
| Silicon, Si | 0.02 |
| Molybdenum, Mo | 0.015 |
| Properties | Metric | Imperial |
|---|---|---|
| Density | 8.387 g/cc | 0.3030 lb/in³ |
| Melting Point | 1265 – 1354 °C | 2309 – 2469 °F |
| Properties | Metric | Imperial |
|---|---|---|
| Hardness, Brinell | 102 | 102 |
| Hardness, Knoop | 414 | 414 |
| Hardness, Rockwell A | 71 | 71 |
| Hardness, Rockwell C | 41 | 41 |
| Hardness, Vickers | 396 | 396 |
| Tensile Strength, Ultimate | 976 MPa | 142000 psi |
| Tensile Strength, Yield | 638 MPa | 92500 psi |
| Elongation at Break | 6% | 6% |
| Modulus of Elasticity | 214 GPa | 31000 ksi |
| Charpy Impact | 8.00 J | 5.90 ft-lb |
- Hardfacing Applications
- Saw Teeth
- Acid-Resistant Machine Parts
- Poppet Valves
- Valve Seats
- Cutting Tools
- Car Engines
- Machine Gun And Rifle Barrels
- Prosthetic Devices
