SAE-AISI 4340 Steel vs. S21904 Stainless Steel
Both SAE-AISI 4340 steel and S21904 stainless steel are iron alloys. They have 67% 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 S21904 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 210 to 360 | |
| 210 to 300 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 12 to 22 | |
| 17 to 51 |
| Fatigue Strength, MPa | 330 to 740 | |
| 380 to 550 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 73 | |
| 78 |
| Shear Strength, MPa | 430 to 770 | |
| 510 to 620 |
| Tensile Strength: Ultimate (UTS), MPa | 690 to 1280 | |
| 700 to 1000 |
| Tensile Strength: Yield (Proof), MPa | 470 to 1150 | |
| 390 to 910 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 290 |
| Maximum Temperature: Mechanical, °C | 430 | |
| 980 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1400 |
| Melting Onset (Solidus), °C | 1420 | |
| 1350 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 44 | |
| 14 |
| Thermal Expansion, µm/m-K | 13 | |
| 17 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.5 | |
| 2.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.6 | |
| 2.9 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 3.5 | |
| 15 |
| Density, g/cm3 | 7.8 | |
| 7.7 |
| Embodied Carbon, kg CO2/kg material | 1.7 | |
| 3.0 |
| Embodied Energy, MJ/kg | 22 | |
| 43 |
| Embodied Water, L/kg | 53 | |
| 160 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 79 to 170 | |
| 160 to 310 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 590 to 3490 | |
| 380 to 2070 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 24 to 45 | |
| 25 to 36 |
| Strength to Weight: Bending, points | 22 to 33 | |
| 23 to 29 |
| Thermal Diffusivity, mm2/s | 12 | |
| 3.8 |
| Thermal Shock Resistance, points | 20 to 38 | |
| 15 to 21 |
Alloy Composition
| Carbon (C), % | 0.38 to 0.43 | |
| 0 to 0.040 |
| Chromium (Cr), % | 0.7 to 0.9 | |
| 19 to 21.5 |
| Iron (Fe), % | 95.1 to 96.3 | |
| 59.5 to 67.4 |
| Manganese (Mn), % | 0.6 to 0.8 | |
| 8.0 to 10 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 0 |
| Nickel (Ni), % | 1.7 to 2.0 | |
| 5.5 to 7.5 |
| Nitrogen (N), % | 0 | |
| 0.15 to 0.4 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.045 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.030 |