ASTM A231 Spring Steel vs. Grade 21 Titanium
ASTM A231 spring steel belongs to the iron alloys classification, while grade 21 titanium belongs to the titanium 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 ASTM A231 spring steel and the bottom bar is grade 21 titanium.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 140 |
| Elongation at Break, % | 14 | |
| 9.0 to 17 |
| Fatigue Strength, MPa | 1000 | |
| 550 to 660 |
| Poisson's Ratio | 0.29 | |
| 0.32 |
| Reduction in Area, % | 46 | |
| 22 |
| Shear Modulus, GPa | 73 | |
| 51 |
| Shear Strength, MPa | 1080 | |
| 550 to 790 |
| Tensile Strength: Ultimate (UTS), MPa | 1790 | |
| 890 to 1340 |
| Tensile Strength: Yield (Proof), MPa | 1570 | |
| 870 to 1170 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 410 |
| Maximum Temperature: Mechanical, °C | 420 | |
| 310 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1740 |
| Melting Onset (Solidus), °C | 1410 | |
| 1690 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 500 |
| Thermal Conductivity, W/m-K | 52 | |
| 7.5 |
| Thermal Expansion, µm/m-K | 13 | |
| 7.1 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.3 | |
| 60 |
| Density, g/cm3 | 7.8 | |
| 5.4 |
| Embodied Carbon, kg CO2/kg material | 2.0 | |
| 32 |
| Embodied Energy, MJ/kg | 28 | |
| 490 |
| Embodied Water, L/kg | 51 | |
| 180 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 230 | |
| 110 to 180 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 32 |
| Strength to Weight: Axial, points | 64 | |
| 46 to 69 |
| Strength to Weight: Bending, points | 42 | |
| 38 to 50 |
| Thermal Diffusivity, mm2/s | 14 | |
| 2.8 |
| Thermal Shock Resistance, points | 53 | |
| 66 to 100 |
Alloy Composition
| Aluminum (Al), % | 0 | |
| 2.5 to 3.5 |
| Carbon (C), % | 0.48 to 0.53 | |
| 0 to 0.050 |
| Chromium (Cr), % | 0.8 to 1.1 | |
| 0 |
| Hydrogen (H), % | 0 | |
| 0 to 0.015 |
| Iron (Fe), % | 96.7 to 97.7 | |
| 0 to 0.4 |
| Manganese (Mn), % | 0.7 to 0.9 | |
| 0 |
| Molybdenum (Mo), % | 0 | |
| 14 to 16 |
| Niobium (Nb), % | 0 | |
| 2.2 to 3.2 |
| Nitrogen (N), % | 0 | |
| 0 to 0.030 |
| Oxygen (O), % | 0 | |
| 0 to 0.17 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.25 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 |
| Titanium (Ti), % | 0 | |
| 76 to 81.2 |
| Vanadium (V), % | 0.15 to 0.3 | |
| 0 |
| Residuals, % | 0 | |
| 0 to 0.4 |