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2024 Aluminum vs. ASTM A387 Grade 21 Steel

2024 aluminum belongs to the aluminum alloys classification, while ASTM A387 grade 21 steel belongs to the iron alloys. There are 30 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 2024 aluminum and the bottom bar is ASTM A387 grade 21 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 71
190
Elongation at Break, % 4.0 to 16
21
Fatigue Strength, MPa 90 to 180
160 to 250
Poisson's Ratio 0.33
0.29
Shear Modulus, GPa 27
74
Shear Strength, MPa 130 to 320
310 to 370
Tensile Strength: Ultimate (UTS), MPa 200 to 540
500 to 590
Tensile Strength: Yield (Proof), MPa 100 to 490
230 to 350

Thermal Properties

Latent Heat of Fusion, J/g 390
260
Maximum Temperature: Mechanical, °C 200
480
Melting Completion (Liquidus), °C 640
1470
Melting Onset (Solidus), °C 500
1430
Specific Heat Capacity, J/kg-K 880
470
Thermal Conductivity, W/m-K 120
41
Thermal Expansion, µm/m-K 23
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 30
7.6
Electrical Conductivity: Equal Weight (Specific), % IACS 90
8.8

Otherwise Unclassified Properties

Base Metal Price, % relative 11
4.1
Density, g/cm3 3.0
7.9
Embodied Carbon, kg CO2/kg material 8.3
1.8
Embodied Energy, MJ/kg 150
23
Embodied Water, L/kg 1140
62

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 20 to 68
84 to 110
Resilience: Unit (Modulus of Resilience), kJ/m3 70 to 1680
140 to 320
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 46
24
Strength to Weight: Axial, points 18 to 50
18 to 21
Strength to Weight: Bending, points 25 to 49
18 to 20
Thermal Diffusivity, mm2/s 46
11
Thermal Shock Resistance, points 8.6 to 24
14 to 17

Alloy Composition

Aluminum (Al), % 90.7 to 94.7
0
Carbon (C), % 0
0.050 to 0.15
Chromium (Cr), % 0 to 0.1
2.8 to 3.3
Copper (Cu), % 3.8 to 4.9
0
Iron (Fe), % 0 to 0.5
94.4 to 96
Magnesium (Mg), % 1.2 to 1.8
0
Manganese (Mn), % 0.3 to 0.9
0.3 to 0.6
Molybdenum (Mo), % 0
0.9 to 1.1
Phosphorus (P), % 0
0 to 0.025
Silicon (Si), % 0 to 0.5
0 to 0.5
Sulfur (S), % 0
0 to 0.025
Titanium (Ti), % 0 to 0.15
0
Zinc (Zn), % 0 to 0.25
0
Zirconium (Zr), % 0 to 0.2
0
Residuals, % 0 to 0.15
0

Comparable Variants