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ACI-ASTM CG8M Steel vs. AZ91D Magnesium

ACI-ASTM CG8M steel belongs to the iron alloys classification, while AZ91D magnesium belongs to the magnesium alloys. There are 31 material properties with values for both materials. Properties with values for just one material (5, 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 ACI-ASTM CG8M steel and the bottom bar is AZ91D magnesium.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 180
60 to 80
Elastic (Young's, Tensile) Modulus, GPa 200
46
Elongation at Break, % 45
2.3 to 4.5
Fatigue Strength, MPa 280
74 to 85
Impact Strength: V-Notched Charpy, J 110
2.7
Poisson's Ratio 0.28
0.29
Shear Modulus, GPa 79
18
Tensile Strength: Ultimate (UTS), MPa 550
160 to 220
Tensile Strength: Yield (Proof), MPa 300
80 to 130

Thermal Properties

Latent Heat of Fusion, J/g 300
350
Maximum Temperature: Mechanical, °C 1020
130
Melting Completion (Liquidus), °C 1450
600
Melting Onset (Solidus), °C 1400
490
Specific Heat Capacity, J/kg-K 470
990
Thermal Conductivity, W/m-K 16
78
Thermal Expansion, µm/m-K 16
27

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
11
Electrical Conductivity: Equal Weight (Specific), % IACS 2.3
58

Otherwise Unclassified Properties

Base Metal Price, % relative 20
12
Density, g/cm3 7.9
1.7
Embodied Carbon, kg CO2/kg material 4.1
22
Embodied Energy, MJ/kg 56
160
Embodied Water, L/kg 160
990

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 210
4.2 to 7.7
Resilience: Unit (Modulus of Resilience), kJ/m3 220
69 to 170
Stiffness to Weight: Axial, points 14
15
Stiffness to Weight: Bending, points 25
69
Strength to Weight: Axial, points 19
26 to 34
Strength to Weight: Bending, points 19
38 to 46
Thermal Diffusivity, mm2/s 4.3
45
Thermal Shock Resistance, points 12
9.5 to 13

Alloy Composition

Aluminum (Al), % 0
8.3 to 9.7
Carbon (C), % 0 to 0.080
0
Chromium (Cr), % 18 to 21
0
Copper (Cu), % 0
0 to 0.030
Iron (Fe), % 58.8 to 70
0 to 0.0050
Magnesium (Mg), % 0
88.7 to 91.2
Manganese (Mn), % 0 to 1.5
0.15 to 0.5
Molybdenum (Mo), % 3.0 to 4.0
0
Nickel (Ni), % 9.0 to 13
0 to 0.0020
Phosphorus (P), % 0 to 0.040
0
Silicon (Si), % 0 to 1.5
0 to 0.1
Sulfur (S), % 0 to 0.040
0
Zinc (Zn), % 0
0.35 to 1.0