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SAE-AISI P21 Steel vs. 7475 Aluminum

SAE-AISI P21 steel belongs to the iron alloys classification, while 7475 aluminum belongs to the aluminum alloys. There are 23 material properties with values for both materials. Properties with values for just one material (8, 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 SAE-AISI P21 steel and the bottom bar is 7475 aluminum.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
70
Poisson's Ratio 0.29
0.32
Shear Modulus, GPa 73
26
Tensile Strength: Ultimate (UTS), MPa 1130
530 to 590

Thermal Properties

Latent Heat of Fusion, J/g 250
380
Melting Completion (Liquidus), °C 1450
640
Melting Onset (Solidus), °C 1410
480
Specific Heat Capacity, J/kg-K 470
870
Thermal Conductivity, W/m-K 41
140 to 160
Thermal Expansion, µm/m-K 12
23

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.9
33 to 42
Electrical Conductivity: Equal Weight (Specific), % IACS 9.0
98 to 120

Otherwise Unclassified Properties

Base Metal Price, % relative 6.5
10
Density, g/cm3 7.9
3.0
Embodied Carbon, kg CO2/kg material 2.3
8.2
Embodied Energy, MJ/kg 32
150
Embodied Water, L/kg 62
1130

Common Calculations

Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
46
Strength to Weight: Axial, points 40
49 to 55
Strength to Weight: Bending, points 31
48 to 52
Thermal Diffusivity, mm2/s 11
53 to 63
Thermal Shock Resistance, points 37
23 to 26

Alloy Composition

Aluminum (Al), % 0
88.6 to 91.6
Carbon (C), % 0.18 to 0.22
0
Chromium (Cr), % 0 to 0.5
0.18 to 0.25
Cobalt (Co), % 1.1 to 1.3
0
Copper (Cu), % 0 to 0.25
1.2 to 1.9
Iron (Fe), % 92.1 to 94.2
0 to 0.12
Magnesium (Mg), % 0
1.9 to 2.6
Manganese (Mn), % 0.35 to 0.72
0 to 0.060
Nickel (Ni), % 3.9 to 4.3
0
Phosphorus (P), % 0 to 0.030
0
Silicon (Si), % 0.2 to 0.4
0 to 0.1
Sulfur (S), % 0 to 0.030
0
Titanium (Ti), % 0
0 to 0.060
Vanadium (V), % 0.15 to 0.25
0
Zinc (Zn), % 0
5.1 to 6.2
Residuals, % 0
0 to 0.15