ASTM A387 Grade 21 Steel vs. SAE-AISI 4340 Steel
Both ASTM A387 grade 21 steel and SAE-AISI 4340 steel are iron alloys. They have a very high 97% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (1, 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 SAE-AISI 4340 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 210 to 360 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 21 | |
| 12 to 22 |
| Fatigue Strength, MPa | 160 to 250 | |
| 330 to 740 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 74 | |
| 73 |
| Shear Strength, MPa | 310 to 370 | |
| 430 to 770 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 690 to 1280 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 470 to 1150 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 430 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1460 |
| 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 | |
| 7.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 8.6 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 3.5 |
| Density, g/cm3 | 7.9 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 1.7 |
| Embodied Energy, MJ/kg | 23 | |
| 22 |
| Embodied Water, L/kg | 62 | |
| 53 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 79 to 170 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 590 to 3490 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 24 to 45 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 22 to 33 |
| Thermal Diffusivity, mm2/s | 11 | |
| 12 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 20 to 38 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 0.7 to 0.9 |
| Iron (Fe), % | 94.4 to 96 | |
| 95.1 to 96.3 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0.6 to 0.8 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0.2 to 0.3 |
| Nickel (Ni), % | 0 | |
| 1.7 to 2.0 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.035 |
| Silicon (Si), % | 0 to 0.5 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.040 |