ASTM A387 Grade 21 Steel vs. Type 4 Niobium
ASTM A387 grade 21 steel belongs to the iron alloys classification, while Type 4 niobium belongs to the otherwise unclassified metals. There are 21 material properties with values for both materials. Properties with values for just one material (11, 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 Type 4 niobium.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 120 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 110 |
| Elongation at Break, % | 21 | |
| 23 |
| Poisson's Ratio | 0.29 | |
| 0.4 |
| Shear Modulus, GPa | 74 | |
| 38 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 220 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 140 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 310 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 270 |
| Thermal Conductivity, W/m-K | 41 | |
| 42 |
| Thermal Expansion, µm/m-K | 13 | |
| 7.3 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.9 | |
| 8.6 |
| Embodied Water, L/kg | 62 | |
| 160 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 44 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 93 |
| Stiffness to Weight: Axial, points | 13 | |
| 6.8 |
| Stiffness to Weight: Bending, points | 24 | |
| 18 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 7.2 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 9.5 |
| Thermal Diffusivity, mm2/s | 11 | |
| 18 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 21 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.010 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 0 |
| Hafnium (Hf), % | 0 | |
| 0 to 0.020 |
| Hydrogen (H), % | 0 | |
| 0 to 0.0015 |
| Iron (Fe), % | 94.4 to 96 | |
| 0 to 0.010 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 to 0.050 |
| Nickel (Ni), % | 0 | |
| 0 to 0.0050 |
| Niobium (Nb), % | 0 | |
| 98.1 to 99.2 |
| Nitrogen (N), % | 0 | |
| 0 to 0.010 |
| Oxygen (O), % | 0 | |
| 0 to 0.025 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 0.0050 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 |
| Tantalum (Ta), % | 0 | |
| 0 to 0.5 |
| Titanium (Ti), % | 0 | |
| 0 to 0.020 |
| Tungsten (W), % | 0 | |
| 0 to 0.050 |
| Zirconium (Zr), % | 0 | |
| 0.8 to 1.2 |