Cromo-Cobalto
Nel campo delle superleghe il cromo-cobalto è quella caratterizzata da importanti proprietà meccaniche come la durezza, la resistenza alla corrosione e alle alte temperature.
Queste tipologie di materiale è principalmente utilizzata in ambito biomedico e dentale, oltre che per applicazioni ingegneristiche sia in ambito sportivo che aeronautico.
Le ottime caratteristiche meccaniche del cromo-cobalto unite alla lavorabilità e all'eccellente resistenza alla corrosione lo rendono ottimale per produrre protesi odontoiatriche e protesi mediche in genere.
Dati Tecnici Materiale
| 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 |