ASTM A387 Grade 21 Steel vs. ASTM A387 Grade 12 Steel
Both ASTM A387 grade 21 steel and ASTM A387 grade 12 steel are iron alloys. They have a very high 98% of their average alloy composition in common.
For each property being compared, the top bar is ASTM A387 grade 21 steel and the bottom bar is ASTM A387 grade 12 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 140 to 160 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 21 | |
| 25 |
| Fatigue Strength, MPa | 160 to 250 | |
| 190 to 230 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 74 | |
| 73 |
| Shear Strength, MPa | 310 to 370 | |
| 300 to 330 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 470 to 520 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 260 to 310 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 430 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1470 |
| Melting Onset (Solidus), °C | 1430 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 41 | |
| 44 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 7.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 8.3 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 2.8 |
| Density, g/cm3 | 7.9 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 1.6 |
| Embodied Energy, MJ/kg | 23 | |
| 21 |
| Embodied Water, L/kg | 62 | |
| 51 |
Common Calculations
| PREN (Pitting Resistance) | 6.4 | |
| 2.7 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 98 to 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 180 to 250 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 16 to 18 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 17 to 18 |
| Thermal Diffusivity, mm2/s | 11 | |
| 12 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 14 to 15 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0.050 to 0.17 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 0.8 to 1.2 |
| Iron (Fe), % | 94.4 to 96 | |
| 97 to 98.2 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0.4 to 0.65 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0.45 to 0.6 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.025 |
| Silicon (Si), % | 0 to 0.5 | |
| 0.15 to 0.4 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.025 |