ASTM A387 Grade 21 Steel vs. Grade 18 Titanium
ASTM A387 grade 21 steel belongs to the iron alloys classification, while grade 18 titanium belongs to the titanium alloys. There are 29 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 A387 grade 21 steel and the bottom bar is grade 18 titanium.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 110 |
| Elongation at Break, % | 21 | |
| 11 to 17 |
| Fatigue Strength, MPa | 160 to 250 | |
| 330 to 480 |
| Poisson's Ratio | 0.29 | |
| 0.32 |
| Shear Modulus, GPa | 74 | |
| 40 |
| Shear Strength, MPa | 310 to 370 | |
| 420 to 590 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 690 to 980 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 540 to 810 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 410 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 330 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1640 |
| Melting Onset (Solidus), °C | 1430 | |
| 1590 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 550 |
| Thermal Conductivity, W/m-K | 41 | |
| 8.3 |
| Thermal Expansion, µm/m-K | 13 | |
| 9.9 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 1.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 2.7 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.9 | |
| 4.5 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 41 |
| Embodied Energy, MJ/kg | 23 | |
| 670 |
| Embodied Water, L/kg | 62 | |
| 270 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 87 to 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 1380 to 3110 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 35 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 43 to 61 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 39 to 49 |
| Thermal Diffusivity, mm2/s | 11 | |
| 3.4 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 47 to 67 |
Alloy Composition
| Aluminum (Al), % | 0 | |
| 2.5 to 3.5 |
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.080 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 0 |
| Hydrogen (H), % | 0 | |
| 0 to 0.015 |
| Iron (Fe), % | 94.4 to 96 | |
| 0 to 0.25 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 |
| Nitrogen (N), % | 0 | |
| 0 to 0.030 |
| Oxygen (O), % | 0 | |
| 0 to 0.15 |
| Palladium (Pd), % | 0 | |
| 0.040 to 0.080 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 |
| Titanium (Ti), % | 0 | |
| 92.5 to 95.5 |
| Vanadium (V), % | 0 | |
| 2.0 to 3.0 |
| Residuals, % | 0 | |
| 0 to 0.4 |