85-platinum 15-iridium vs. ASTM A387 Grade 21 Steel
85-platinum 15-iridium belongs to the otherwise unclassified metals classification, while ASTM A387 grade 21 steel belongs to the iron alloys. There are 19 material properties with values for both materials. Properties with values for just one material (13, 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 85-platinum 15-iridium and the bottom bar is ASTM A387 grade 21 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 220 | |
| 190 |
| Elongation at Break, % | 5.5 to 34 | |
| 21 |
| Poisson's Ratio | 0.38 | |
| 0.29 |
| Shear Modulus, GPa | 81 | |
| 74 |
| Shear Strength, MPa | 370 to 420 | |
| 310 to 370 |
| Tensile Strength: Ultimate (UTS), MPa | 560 to 730 | |
| 500 to 590 |
Thermal Properties
| Latent Heat of Fusion, J/g | 110 | |
| 260 |
| Melting Completion (Liquidus), °C | 1820 | |
| 1470 |
| Melting Onset (Solidus), °C | 1790 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 130 | |
| 470 |
| Thermal Expansion, µm/m-K | 8.4 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 6.2 | |
| 7.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.6 | |
| 8.8 |
Otherwise Unclassified Properties
| Density, g/cm3 | 22 | |
| 7.9 |
Common Calculations
| Stiffness to Weight: Axial, points | 5.7 | |
| 13 |
| Stiffness to Weight: Bending, points | 9.3 | |
| 24 |
| Strength to Weight: Axial, points | 7.1 to 9.3 | |
| 18 to 21 |
| Strength to Weight: Bending, points | 6.9 to 8.3 | |
| 18 to 20 |
| Thermal Shock Resistance, points | 21 to 28 | |
| 14 to 17 |
Alloy Composition
| Carbon (C), % | 0 | |
| 0.050 to 0.15 |
| Chromium (Cr), % | 0 | |
| 2.8 to 3.3 |
| Iridium (Ir), % | 14.5 to 15.5 | |
| 0 |
| Iron (Fe), % | 0 | |
| 94.4 to 96 |
| Manganese (Mn), % | 0 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 0 | |
| 0.9 to 1.1 |
| Phosphorus (P), % | 0 | |
| 0 to 0.025 |
| Platinum (Pt), % | 84.3 to 85.5 | |
| 0 |
| Silicon (Si), % | 0 | |
| 0 to 0.5 |
| Sulfur (S), % | 0 | |
| 0 to 0.025 |
| Residuals, % | 0 to 0.2 | |
| 0 |