AZ91B Magnesium vs. SAE-AISI M4 Steel
AZ91B magnesium belongs to the magnesium alloys classification, while SAE-AISI M4 steel belongs to the iron alloys. There are 21 material properties with values for both materials. Properties with values for just one material (13, 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 AZ91B magnesium and the bottom bar is SAE-AISI M4 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 46 | |
| 200 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 18 | |
| 76 |
| Tensile Strength: Ultimate (UTS), MPa | 240 | |
| 770 to 2150 |
Thermal Properties
| Latent Heat of Fusion, J/g | 360 | |
| 260 |
| Melting Completion (Liquidus), °C | 600 | |
| 1610 |
| Melting Onset (Solidus), °C | 470 | |
| 1560 |
| Specific Heat Capacity, J/kg-K | 990 | |
| 440 |
| Thermal Conductivity, W/m-K | 73 | |
| 25 |
| Thermal Expansion, µm/m-K | 26 | |
| 12 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 12 | |
| 25 |
| Density, g/cm3 | 1.7 | |
| 8.3 |
| Embodied Carbon, kg CO2/kg material | 22 | |
| 14 |
| Embodied Energy, MJ/kg | 160 | |
| 210 |
| Embodied Water, L/kg | 990 | |
| 110 |
Common Calculations
| Stiffness to Weight: Axial, points | 15 | |
| 13 |
| Stiffness to Weight: Bending, points | 69 | |
| 23 |
| Strength to Weight: Axial, points | 38 | |
| 26 to 72 |
| Strength to Weight: Bending, points | 49 | |
| 23 to 45 |
| Thermal Diffusivity, mm2/s | 42 | |
| 6.9 |
| Thermal Shock Resistance, points | 14 | |
| 24 to 68 |
Alloy Composition
| Aluminum (Al), % | 8.3 to 9.7 | |
| 0 |
| Carbon (C), % | 0 | |
| 1.3 to 1.4 |
| Chromium (Cr), % | 0 | |
| 3.8 to 4.8 |
| Copper (Cu), % | 0 to 0.35 | |
| 0 to 0.25 |
| Iron (Fe), % | 0 | |
| 75.9 to 81.4 |
| Magnesium (Mg), % | 87.9 to 91.2 | |
| 0 |
| Manganese (Mn), % | 0.13 to 0.5 | |
| 0.15 to 0.4 |
| Molybdenum (Mo), % | 0 | |
| 4.3 to 5.5 |
| Nickel (Ni), % | 0 to 0.030 | |
| 0 to 0.3 |
| Phosphorus (P), % | 0 | |
| 0 to 0.030 |
| Silicon (Si), % | 0 to 0.5 | |
| 0.2 to 0.45 |
| Sulfur (S), % | 0 | |
| 0 to 0.030 |
| Tungsten (W), % | 0 | |
| 5.3 to 6.5 |
| Vanadium (V), % | 0 | |
| 3.8 to 4.5 |
| Zinc (Zn), % | 0.35 to 1.0 | |
| 0 |