SAE-AISI 4340 Steel vs. AISI 321 Stainless Steel
Both SAE-AISI 4340 steel and AISI 321 stainless steel are iron alloys. They have 73% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.
For each property being compared, the top bar is SAE-AISI 4340 steel and the bottom bar is AISI 321 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 210 to 360 | |
| 170 to 210 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 12 to 22 | |
| 34 to 50 |
| Fatigue Strength, MPa | 330 to 740 | |
| 220 to 270 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 73 | |
| 77 |
| Shear Strength, MPa | 430 to 770 | |
| 420 to 460 |
| Tensile Strength: Ultimate (UTS), MPa | 690 to 1280 | |
| 590 to 690 |
| Tensile Strength: Yield (Proof), MPa | 470 to 1150 | |
| 220 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 290 |
| Maximum Temperature: Mechanical, °C | 430 | |
| 870 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1430 |
| Melting Onset (Solidus), °C | 1420 | |
| 1400 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 44 | |
| 16 |
| Thermal Expansion, µm/m-K | 13 | |
| 17 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.5 | |
| 2.4 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.6 | |
| 2.7 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 3.5 | |
| 16 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.7 | |
| 3.2 |
| Embodied Energy, MJ/kg | 22 | |
| 45 |
| Embodied Water, L/kg | 53 | |
| 140 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 79 to 170 | |
| 190 to 230 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 590 to 3490 | |
| 130 to 310 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 24 to 45 | |
| 21 to 25 |
| Strength to Weight: Bending, points | 22 to 33 | |
| 20 to 22 |
| Thermal Diffusivity, mm2/s | 12 | |
| 4.1 |
| Thermal Shock Resistance, points | 20 to 38 | |
| 13 to 15 |
Alloy Composition
| Carbon (C), % | 0.38 to 0.43 | |
| 0 to 0.080 |
| Chromium (Cr), % | 0.7 to 0.9 | |
| 17 to 19 |
| Iron (Fe), % | 95.1 to 96.3 | |
| 65.3 to 74 |
| Manganese (Mn), % | 0.6 to 0.8 | |
| 0 to 2.0 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 0 |
| Nickel (Ni), % | 1.7 to 2.0 | |
| 9.0 to 12 |
| Nitrogen (N), % | 0 | |
| 0 to 0.1 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.045 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0 to 0.75 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.030 |
| Titanium (Ti), % | 0 | |
| 0 to 0.7 |