PEEK vs. R31538 Cobalt
PEEK and R31538 cobalt belong to fundamentally different material chemistries. PEEK is a polymeric material, while R31538 cobalt is a metal. Therefore, their performance will be even more dissimilar than would be suggested by the difference in properties. There are 14 material properties with values for both materials. Properties with values for just one material (30, in this case) are not shown. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is PEEK and the bottom bar is R31538 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 4.0 to 24 | |
| 220 |
| Elongation at Break, % | 1.6 to 43 | |
| 13 to 23 |
| Tensile Strength: Ultimate (UTS), MPa | 97 to 200 | |
| 1020 to 1360 |
Thermal Properties
| Melting Onset (Solidus), °C | 340 | |
| 1290 |
| Specific Heat Capacity, J/kg-K | 1390 to 1700 | |
| 450 |
| Thermal Conductivity, W/m-K | 0.25 to 0.93 | |
| 13 |
| Thermal Expansion, µm/m-K | 15 to 52 | |
| 13 |
Otherwise Unclassified Properties
| Density, g/cm3 | 1.3 to 1.5 | |
| 8.4 |
Common Calculations
| Stiffness to Weight: Axial, points | 1.5 to 10 | |
| 15 |
| Stiffness to Weight: Bending, points | 36 to 73 | |
| 24 |
| Strength to Weight: Axial, points | 20 to 41 | |
| 34 to 45 |
| Strength to Weight: Bending, points | 36 to 55 | |
| 27 to 32 |
| Thermal Diffusivity, mm2/s | 0.1 to 0.51 | |
| 3.5 |
| Thermal Shock Resistance, points | 34 to 57 | |
| 25 to 33 |