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3105 Aluminum vs. S81921 Stainless Steel

3105 aluminum belongs to the aluminum alloys classification, while S81921 stainless steel belongs to the iron alloys. There are 31 material properties with values for both materials. Properties with values for just one material (4, 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 3105 aluminum and the bottom bar is S81921 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 29 to 67
260
Elastic (Young's, Tensile) Modulus, GPa 69
200
Elongation at Break, % 1.1 to 20
29
Fatigue Strength, MPa 39 to 95
370
Poisson's Ratio 0.33
0.28
Shear Modulus, GPa 26
79
Shear Strength, MPa 77 to 140
460
Tensile Strength: Ultimate (UTS), MPa 120 to 240
710
Tensile Strength: Yield (Proof), MPa 46 to 220
500

Thermal Properties

Latent Heat of Fusion, J/g 400
290
Maximum Temperature: Mechanical, °C 180
990
Melting Completion (Liquidus), °C 660
1430
Melting Onset (Solidus), °C 640
1390
Specific Heat Capacity, J/kg-K 900
480
Thermal Conductivity, W/m-K 170
15
Thermal Expansion, µm/m-K 24
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 44
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 140
2.5

Otherwise Unclassified Properties

Base Metal Price, % relative 9.5
14
Density, g/cm3 2.8
7.7
Embodied Carbon, kg CO2/kg material 8.2
2.9
Embodied Energy, MJ/kg 150
41
Embodied Water, L/kg 1180
150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 2.6 to 19
180
Resilience: Unit (Modulus of Resilience), kJ/m3 15 to 340
630
Stiffness to Weight: Axial, points 14
14
Stiffness to Weight: Bending, points 50
25
Strength to Weight: Axial, points 12 to 24
25
Strength to Weight: Bending, points 20 to 31
23
Thermal Diffusivity, mm2/s 68
4.0
Thermal Shock Resistance, points 5.2 to 11
20

Alloy Composition

Aluminum (Al), % 96 to 99.5
0
Carbon (C), % 0
0 to 0.030
Chromium (Cr), % 0 to 0.2
19 to 22
Copper (Cu), % 0 to 0.3
0
Iron (Fe), % 0 to 0.7
66.7 to 75.9
Magnesium (Mg), % 0.2 to 0.8
0
Manganese (Mn), % 0.3 to 0.8
2.0 to 4.0
Molybdenum (Mo), % 0
1.0 to 2.0
Nickel (Ni), % 0
2.0 to 4.0
Nitrogen (N), % 0
0.14 to 0.2
Phosphorus (P), % 0
0 to 0.040
Silicon (Si), % 0 to 0.6
0 to 1.0
Sulfur (S), % 0
0 to 0.030
Titanium (Ti), % 0 to 0.1
0
Zinc (Zn), % 0 to 0.4
0
Residuals, % 0 to 0.15
0