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4145 Aluminum vs. SAE-AISI P21 Steel

4145 aluminum belongs to the aluminum alloys classification, while SAE-AISI P21 steel belongs to the iron alloys. There are 23 material properties with values for both materials. Properties with values for just one material (9, 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 4145 aluminum and the bottom bar is SAE-AISI P21 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 73
190
Poisson's Ratio 0.33
0.29
Shear Modulus, GPa 28
73
Tensile Strength: Ultimate (UTS), MPa 120
1130

Thermal Properties

Latent Heat of Fusion, J/g 540
250
Melting Completion (Liquidus), °C 590
1450
Melting Onset (Solidus), °C 520
1410
Specific Heat Capacity, J/kg-K 880
470
Thermal Conductivity, W/m-K 100
41
Thermal Expansion, µm/m-K 21
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 26
7.9
Electrical Conductivity: Equal Weight (Specific), % IACS 84
9.0

Otherwise Unclassified Properties

Base Metal Price, % relative 10
6.5
Density, g/cm3 2.8
7.9
Embodied Carbon, kg CO2/kg material 7.6
2.3
Embodied Energy, MJ/kg 140
32
Embodied Water, L/kg 1040
62

Common Calculations

Stiffness to Weight: Axial, points 14
13
Stiffness to Weight: Bending, points 50
24
Strength to Weight: Axial, points 12
40
Strength to Weight: Bending, points 19
31
Thermal Diffusivity, mm2/s 42
11
Thermal Shock Resistance, points 5.5
37

Alloy Composition

Aluminum (Al), % 83 to 87.4
0
Carbon (C), % 0
0.18 to 0.22
Chromium (Cr), % 0 to 0.15
0 to 0.5
Cobalt (Co), % 0
1.1 to 1.3
Copper (Cu), % 3.3 to 4.7
0 to 0.25
Iron (Fe), % 0 to 0.8
92.1 to 94.2
Magnesium (Mg), % 0 to 0.15
0
Manganese (Mn), % 0 to 0.15
0.35 to 0.72
Nickel (Ni), % 0
3.9 to 4.3
Phosphorus (P), % 0
0 to 0.030
Silicon (Si), % 9.3 to 10.7
0.2 to 0.4
Sulfur (S), % 0
0 to 0.030
Vanadium (V), % 0
0.15 to 0.25
Zinc (Zn), % 0 to 0.2
0
Residuals, % 0 to 0.15
0