AZ91C Magnesium vs. SAE-AISI 4340M Steel
AZ91C magnesium belongs to the magnesium alloys classification, while SAE-AISI 4340M steel belongs to the iron alloys. There are 30 material properties with values for both materials. Properties with values for just one material (6, in this case) are not shown. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is AZ91C magnesium and the bottom bar is SAE-AISI 4340M steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 46 | |
| 190 |
| Elongation at Break, % | 2.3 to 7.9 | |
| 6.0 |
| Fatigue Strength, MPa | 56 to 85 | |
| 690 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 18 | |
| 72 |
| Shear Strength, MPa | 96 to 160 | |
| 1360 |
| Tensile Strength: Ultimate (UTS), MPa | 170 to 270 | |
| 2340 |
| Tensile Strength: Yield (Proof), MPa | 83 to 130 | |
| 1240 |
Thermal Properties
| Latent Heat of Fusion, J/g | 350 | |
| 280 |
| Maximum Temperature: Mechanical, °C | 130 | |
| 430 |
| Melting Completion (Liquidus), °C | 600 | |
| 1440 |
| Melting Onset (Solidus), °C | 470 | |
| 1400 |
| Specific Heat Capacity, J/kg-K | 990 | |
| 480 |
| Thermal Conductivity, W/m-K | 73 | |
| 38 |
| Thermal Expansion, µm/m-K | 26 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 9.9 to 12 | |
| 7.8 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 52 to 60 | |
| 9.1 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 12 | |
| 3.9 |
| Density, g/cm3 | 1.7 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 22 | |
| 1.9 |
| Embodied Energy, MJ/kg | 160 | |
| 26 |
| Embodied Water, L/kg | 990 | |
| 55 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 3.2 to 16 | |
| 120 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 75 to 180 | |
| 4120 |
| Stiffness to Weight: Axial, points | 15 | |
| 13 |
| Stiffness to Weight: Bending, points | 69 | |
| 25 |
| Strength to Weight: Axial, points | 27 to 43 | |
| 84 |
| Strength to Weight: Bending, points | 39 to 53 | |
| 51 |
| Thermal Diffusivity, mm2/s | 43 | |
| 10 |
| Thermal Shock Resistance, points | 9.9 to 16 | |
| 70 |
Alloy Composition
| Aluminum (Al), % | 8.1 to 9.3 | |
| 0 |
| Carbon (C), % | 0 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 0 | |
| 0.7 to 1.0 |
| Copper (Cu), % | 0 to 0.1 | |
| 0 |
| Iron (Fe), % | 0 | |
| 93.3 to 94.8 |
| Magnesium (Mg), % | 88.6 to 91.4 | |
| 0 |
| Manganese (Mn), % | 0.13 to 0.35 | |
| 0.65 to 0.9 |
| Molybdenum (Mo), % | 0 | |
| 0.35 to 0.45 |
| Nickel (Ni), % | 0 to 0.010 | |
| 1.7 to 2.0 |
| Phosphorus (P), % | 0 | |
| 0 to 0.012 |
| Silicon (Si), % | 0 to 0.3 | |
| 1.5 to 1.8 |
| Sulfur (S), % | 0 | |
| 0 to 0.012 |
| Vanadium (V), % | 0 | |
| 0.050 to 0.1 |
| Zinc (Zn), % | 0.4 to 1.0 | |
| 0 |
| Residuals, % | 0 to 0.3 | |
| 0 |