Cobalt-Chrome
Of all superalloys, cobalt-chrome is that characterised by significant mechanical properties such as hardness, resistance to corrosion and high temperatures.
These type of material is mainly used in biomedical and dental fields, as well as for engineering applications (e.g. aircraft engines).
The excellent mechanical properties of chromium-cobalt combined with excellent machinability and corrosion resistance make it optimal for producing dental prostheses and medical implants in general.
Technical Data of the material and physical and chemical properties
| Technical Data | Test Method | |
| Typical achievable part accuracy, small parts | - - - - - - - | approx. ± 20 – 50 μm |
| Typical achievable part accuracy, large parts | - - - - - - - | approx. ± 50 – 200 μm |
| Min. wall thickness [1] | - - - - - - - | approx. 0.3 mm |
|
Surface roughness [2] as built, MP1 Performance (40 μm) |
- - - - - - - | Ra 7 - 10 μm, Rz 35 - 50 μm |
| Surface roughness [2] after polishing | - - - - - - - | Rz up to < 1 μm |
| Physical and Chemical properties of parts | Test Method | |
| Material composition | - - - - - - - |
Co (60 - 65 wt-%) Cr (26 - 30 wt-%) Mo (5 - 7 wt-% ) Si (≤ 1.0 wt-%) Mn (≤ 1.0 wt-%) Fe (≤ 0.75 wt-%) C (≤ 0.16 wt-%) Ni (≤ 0.10 wt-%) |
| Relative density | - - - - - - - | approx. 100 % |
| Density | - - - - - - - | approx. 8.3 g/cm3 |
| Mechanical properties of parts at 20°C (68°F) | Test Method | As Built | Stress Relieved [3] |
| Tensile strength [4] in horizontal direction (XY) |
ISO 6892-1:2009(B) Annex D |
1350 ± 100 MPa 196 ± 15 ksi |
1100 ± 100 MPa 160 ± 15 ksi |
| Tensile strength [4] in vertical direction (Z) |
ISO 6892-1:2009(B) Annex D |
1200 ± 150 MPa 174 ± 22 ksi |
1100 ± 100 MPa 160 ± 15 ksi |
| Yield strength (Rp 0.2 %) [4] in horizontal direction (XY) |
ISO 6892-1:2009(B) Annex D |
1060 ± 100 MPa 154 ± 15 ksi |
600 ± 50 MPa 87 ± 7 ksi |
| Yield strength (Rp 0.2 %) [4] in vertical direction (Z) |
ISO 6892-1:2009(B) Annex D |
800 ± 100 MPa 116 ± 15 ksi |
600 ± 50 MPa 87 ± 7 ksi |
| Modulus of elasticity [4] in horizontal direction (XY) |
ISO 6892-1:2009(B) Annex D |
200 ± 20 GPa 29 ± 3 Msi |
200 ± 20 GPa 29 ± 3 Msi |
| Modulus of elasticity [4] in vertical direction (Z) |
ISO 6892-1:2009(B) Annex D |
190 ± 20 GPa 28 ± 3 Msi |
200 ± 20 GPa 29 ± 3 Msi |
| Elongation at break [4] in horizontal direction (XY) |
ISO 6892-1:2009(B) Annex D |
(11 ± 3) % | min. 20% |
| Elongation at break [4] in vertical direction (Z) |
ISO 6892-1:2009(B) Annex D |
(24 ± 4) % | min. 20% |
| Hardness [6] | EN ISO 6508-1 | approx. 35 - 45 HRC | - - - - - - - |
| Fatigue life [5] max. stress to reach 10 million cycles | ASTM E466:1996 |
approx. 560 MPa 81 ksi |
- - - - - - - |
| Fatigue life [5] max. stress to reach 1 million cycles | ASTM E466:1996 |
approx. 660 MPa 96 ks |
- - - - - - - |
| Thermal properties of parts | Test Method | As Built |
| Coefficient of thermal expansion over 20 - 500 °C (68 - 932 °F) | - - - - - - - |
typ. 13.6 x 10-6 m/m °C typ. 7.6 x 10-6 in/in °F |
| Coefficient of thermal expansion over 500 – 1000 °C (932-1832 °F) | - - - - - - - |
typ. 15.1 x 10-6 m/m °C typ. 8.4 x 10-6 in/in °F |
| Thermal conductivity at 20 °C (68 °F) | - - - - - - - |
typ. 13 W/m °C typ. 90 Btu in/(h ft2 °F) |
| Thermal conductivity at 300 °C (572 °F) | - - - - - - - |
typ. 18 W/m °C typ. 125 Btu in/(h ft2 °F) |
| Thermal conductivity at 500 °C (932 °F) | - - - - - - - |
typ. 22 W/m °C typ. 153 Btu in/(h ft2 °F) |
| Thermal conductivity at 1000 °C (1832 °F) | - - - - - - - |
typ. 33 W/m °C typ. 229 Btu in/(h ft2 °F) |
| Maximum operating temperature | - - - - - - - |
approx. 1150 °C approx. 2100 °F |
| Melting range | - - - - - - - |
1350 - 1430 °C 2460 - 2600 °F |