ASTM A387 Grade 21 Steel vs. Ductile Cast Iron
Both ASTM A387 grade 21 steel and ductile cast iron are iron alloys. They have a moderately high 95% of their average alloy composition in common. There are 30 material properties with values for both materials. Properties with values for just one material (3, 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 ductile cast iron.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 160 to 310 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 170 to 180 |
| Elongation at Break, % | 21 | |
| 2.1 to 20 |
| Poisson's Ratio | 0.29 | |
| 0.28 to 0.31 |
| Shear Modulus, GPa | 74 | |
| 64 to 70 |
| Shear Strength, MPa | 310 to 370 | |
| 420 to 800 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 460 to 920 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 310 to 670 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 270 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 290 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1160 |
| Melting Onset (Solidus), °C | 1430 | |
| 1120 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 490 |
| Thermal Conductivity, W/m-K | 41 | |
| 31 to 36 |
| Thermal Expansion, µm/m-K | 13 | |
| 11 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 7.4 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 8.8 to 9.4 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 1.9 |
| Density, g/cm3 | 7.9 | |
| 7.1 to 7.5 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 1.5 |
| Embodied Energy, MJ/kg | 23 | |
| 21 |
| Embodied Water, L/kg | 62 | |
| 43 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 17 to 80 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 280 to 1330 |
| Stiffness to Weight: Axial, points | 13 | |
| 12 to 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 to 26 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 17 to 35 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 18 to 29 |
| Thermal Diffusivity, mm2/s | 11 | |
| 8.9 to 10 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 17 to 35 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 3.0 to 3.5 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 0 |
| Iron (Fe), % | 94.4 to 96 | |
| 93.7 to 95.5 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.080 |
| Silicon (Si), % | 0 to 0.5 | |
| 1.5 to 2.8 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 |