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AZ91B Magnesium vs. ASTM A372 Grade M Steel

AZ91B magnesium belongs to the magnesium alloys classification, while ASTM A372 grade M steel belongs to the iron alloys. There are 31 material properties with values for both materials. Properties with values for just one material (3, 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 ASTM A372 grade M steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 63
240 to 280
Elastic (Young's, Tensile) Modulus, GPa 46
190
Elongation at Break, % 5.0
18 to 21
Fatigue Strength, MPa 79
450 to 520
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 18
73
Shear Strength, MPa 140
510 to 570
Tensile Strength: Ultimate (UTS), MPa 240
810 to 910
Tensile Strength: Yield (Proof), MPa 160
660 to 770

Thermal Properties

Latent Heat of Fusion, J/g 360
250
Maximum Temperature: Mechanical, °C 130
450
Melting Completion (Liquidus), °C 600
1460
Melting Onset (Solidus), °C 470
1420
Specific Heat Capacity, J/kg-K 990
470
Thermal Conductivity, W/m-K 73
46
Thermal Expansion, µm/m-K 26
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 11
8.0
Electrical Conductivity: Equal Weight (Specific), % IACS 58
9.1

Otherwise Unclassified Properties

Base Metal Price, % relative 12
5.0
Density, g/cm3 1.7
7.9
Embodied Carbon, kg CO2/kg material 22
2.0
Embodied Energy, MJ/kg 160
27
Embodied Water, L/kg 990
61

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 11
160
Resilience: Unit (Modulus of Resilience), kJ/m3 280
1140 to 1580
Stiffness to Weight: Axial, points 15
13
Stiffness to Weight: Bending, points 69
24
Strength to Weight: Axial, points 38
29 to 32
Strength to Weight: Bending, points 49
24 to 27
Thermal Diffusivity, mm2/s 42
12
Thermal Shock Resistance, points 14
24 to 27

Alloy Composition

Aluminum (Al), % 8.3 to 9.7
0
Carbon (C), % 0
0 to 0.23
Chromium (Cr), % 0
1.5 to 2.0
Copper (Cu), % 0 to 0.35
0
Iron (Fe), % 0
92.5 to 95.1
Magnesium (Mg), % 87.9 to 91.2
0
Manganese (Mn), % 0.13 to 0.5
0.2 to 0.4
Molybdenum (Mo), % 0
0.4 to 0.6
Nickel (Ni), % 0 to 0.030
2.8 to 3.9
Phosphorus (P), % 0
0 to 0.015
Silicon (Si), % 0 to 0.5
0 to 0.3
Sulfur (S), % 0
0 to 0.010
Vanadium (V), % 0
0 to 0.080
Zinc (Zn), % 0.35 to 1.0
0