Grade 21 Titanium vs. SAE-AISI 8740 Steel
Grade 21 titanium belongs to the titanium alloys classification, while SAE-AISI 8740 steel belongs to the iron alloys. There are 28 material properties with values for both materials. Properties with values for just one material (4, in this case) are not shown.
For each property being compared, the top bar is grade 21 titanium and the bottom bar is SAE-AISI 8740 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 140 | |
| 190 |
| Elongation at Break, % | 9.0 to 17 | |
| 11 to 23 |
| Fatigue Strength, MPa | 550 to 660 | |
| 270 to 350 |
| Poisson's Ratio | 0.32 | |
| 0.29 |
| Shear Modulus, GPa | 51 | |
| 73 |
| Shear Strength, MPa | 550 to 790 | |
| 370 to 400 |
| Tensile Strength: Ultimate (UTS), MPa | 890 to 1340 | |
| 580 to 670 |
| Tensile Strength: Yield (Proof), MPa | 870 to 1170 | |
| 380 to 570 |
Thermal Properties
| Latent Heat of Fusion, J/g | 410 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 310 | |
| 410 |
| Melting Completion (Liquidus), °C | 1740 | |
| 1460 |
| Melting Onset (Solidus), °C | 1690 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 500 | |
| 470 |
| Thermal Conductivity, W/m-K | 7.5 | |
| 39 |
| Thermal Expansion, µm/m-K | 7.1 | |
| 13 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 60 | |
| 2.6 |
| Density, g/cm3 | 5.4 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 32 | |
| 1.5 |
| Embodied Energy, MJ/kg | 490 | |
| 20 |
| Embodied Water, L/kg | 180 | |
| 50 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 110 to 180 | |
| 71 to 120 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 2760 to 5010 | |
| 390 to 850 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 32 | |
| 24 |
| Strength to Weight: Axial, points | 46 to 69 | |
| 20 to 24 |
| Strength to Weight: Bending, points | 38 to 50 | |
| 20 to 22 |
| Thermal Diffusivity, mm2/s | 2.8 | |
| 10 |
| Thermal Shock Resistance, points | 66 to 100 | |
| 17 to 20 |
Alloy Composition
| Aluminum (Al), % | 2.5 to 3.5 | |
| 0 |
| Carbon (C), % | 0 to 0.050 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 0 | |
| 0.4 to 0.6 |
| Hydrogen (H), % | 0 to 0.015 | |
| 0 |
| Iron (Fe), % | 0 to 0.4 | |
| 96.5 to 97.7 |
| Manganese (Mn), % | 0 | |
| 0.75 to 1.0 |
| Molybdenum (Mo), % | 14 to 16 | |
| 0.2 to 0.3 |
| Nickel (Ni), % | 0 | |
| 0.4 to 0.7 |
| Niobium (Nb), % | 2.2 to 3.2 | |
| 0 |
| Nitrogen (N), % | 0 to 0.030 | |
| 0 |
| Oxygen (O), % | 0 to 0.17 | |
| 0 |
| Phosphorus (P), % | 0 | |
| 0 to 0.035 |
| Silicon (Si), % | 0.15 to 0.25 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.040 |
| Titanium (Ti), % | 76 to 81.2 | |
| 0 |
| Residuals, % | 0 to 0.4 | |
| 0 |