ASTM A372 Grade A Steel vs. SAE-AISI 4340 Steel
Both ASTM A372 grade A steel and SAE-AISI 4340 steel are iron alloys. They have a very high 97% of their average alloy composition in common.
For each property being compared, the top bar is ASTM A372 grade A steel and the bottom bar is SAE-AISI 4340 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 140 | |
| 210 to 360 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 22 | |
| 12 to 22 |
| Fatigue Strength, MPa | 190 | |
| 330 to 740 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Shear Strength, MPa | 320 | |
| 430 to 770 |
| Tensile Strength: Ultimate (UTS), MPa | 500 | |
| 690 to 1280 |
| Tensile Strength: Yield (Proof), MPa | 270 | |
| 470 to 1150 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 400 | |
| 430 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1460 |
| Melting Onset (Solidus), °C | 1420 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 52 | |
| 44 |
| Thermal Expansion, µm/m-K | 12 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.1 | |
| 7.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.1 | |
| 8.6 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 1.8 | |
| 3.5 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.4 | |
| 1.7 |
| Embodied Energy, MJ/kg | 18 | |
| 22 |
| Embodied Water, L/kg | 45 | |
| 53 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 95 | |
| 79 to 170 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 200 | |
| 590 to 3490 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 18 | |
| 24 to 45 |
| Strength to Weight: Bending, points | 18 | |
| 22 to 33 |
| Thermal Diffusivity, mm2/s | 14 | |
| 12 |
| Thermal Shock Resistance, points | 16 | |
| 20 to 38 |
Alloy Composition
| Carbon (C), % | 0 to 0.3 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 0 | |
| 0.7 to 0.9 |
| Iron (Fe), % | 98.3 to 99.85 | |
| 95.1 to 96.3 |
| Manganese (Mn), % | 0 to 1.0 | |
| 0.6 to 0.8 |
| Molybdenum (Mo), % | 0 | |
| 0.2 to 0.3 |
| Nickel (Ni), % | 0 | |
| 1.7 to 2.0 |
| Phosphorus (P), % | 0 to 0.015 | |
| 0 to 0.035 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.040 |