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AZ91A Magnesium vs. SAE-AISI 81B45 Steel

AZ91A magnesium belongs to the magnesium alloys classification, while SAE-AISI 81B45 steel belongs to the iron alloys. There are 31 material properties with values for both materials. Properties with values for just one material (2, 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 AZ91A magnesium and the bottom bar is SAE-AISI 81B45 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 63
160 to 200
Elastic (Young's, Tensile) Modulus, GPa 46
190
Elongation at Break, % 5.0
12 to 24
Fatigue Strength, MPa 99
250 to 350
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 18
73
Shear Strength, MPa 140
340 to 400
Tensile Strength: Ultimate (UTS), MPa 240
540 to 670
Tensile Strength: Yield (Proof), MPa 160
350 to 560

Thermal Properties

Latent Heat of Fusion, J/g 360
250
Maximum Temperature: Mechanical, °C 130
410
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
40
Thermal Expansion, µm/m-K 26
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 10
7.2
Electrical Conductivity: Equal Weight (Specific), % IACS 52
8.3

Otherwise Unclassified Properties

Base Metal Price, % relative 12
2.3
Density, g/cm3 1.7
7.8
Embodied Carbon, kg CO2/kg material 22
1.5
Embodied Energy, MJ/kg 160
20
Embodied Water, L/kg 990
49

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 11
77 to 110
Resilience: Unit (Modulus of Resilience), kJ/m3 280
320 to 840
Stiffness to Weight: Axial, points 15
13
Stiffness to Weight: Bending, points 69
24
Strength to Weight: Axial, points 38
19 to 24
Strength to Weight: Bending, points 49
19 to 22
Thermal Diffusivity, mm2/s 42
11
Thermal Shock Resistance, points 14
17 to 21

Alloy Composition

Aluminum (Al), % 8.3 to 9.7
0
Boron (B), % 0
0.00050 to 0.0030
Carbon (C), % 0
0.43 to 0.48
Chromium (Cr), % 0
0.35 to 0.55
Copper (Cu), % 0 to 0.1
0
Iron (Fe), % 0
97 to 98
Magnesium (Mg), % 88.2 to 91.2
0
Manganese (Mn), % 0.13 to 0.5
0.75 to 1.0
Molybdenum (Mo), % 0
0.080 to 0.15
Nickel (Ni), % 0 to 0.030
0.2 to 0.4
Phosphorus (P), % 0
0 to 0.035
Silicon (Si), % 0 to 0.5
0.15 to 0.35
Sulfur (S), % 0
0 to 0.040
Zinc (Zn), % 0.35 to 1.0
0