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SAE-AISI 8645 Steel vs. 2618 Aluminum

SAE-AISI 8645 steel belongs to the iron alloys classification, while 2618 aluminum belongs to the aluminum alloys. 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 8645 steel and the bottom bar is 2618 aluminum.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 180 to 200
120
Elastic (Young's, Tensile) Modulus, GPa 190
71
Elongation at Break, % 12 to 23
5.8
Fatigue Strength, MPa 280 to 350
110
Poisson's Ratio 0.29
0.33
Shear Modulus, GPa 73
27
Shear Strength, MPa 380 to 400
260
Tensile Strength: Ultimate (UTS), MPa 600 to 670
420
Tensile Strength: Yield (Proof), MPa 390 to 560
350

Thermal Properties

Latent Heat of Fusion, J/g 250
390
Maximum Temperature: Mechanical, °C 410
210
Melting Completion (Liquidus), °C 1460
640
Melting Onset (Solidus), °C 1420
550
Specific Heat Capacity, J/kg-K 470
880
Thermal Conductivity, W/m-K 39
160
Thermal Expansion, µm/m-K 13
22

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.3
37
Electrical Conductivity: Equal Weight (Specific), % IACS 8.4
110

Otherwise Unclassified Properties

Base Metal Price, % relative 2.6
11
Density, g/cm3 7.8
2.9
Embodied Carbon, kg CO2/kg material 1.5
8.3
Embodied Energy, MJ/kg 20
150
Embodied Water, L/kg 50
1150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 77 to 120
23
Resilience: Unit (Modulus of Resilience), kJ/m3 420 to 840
850
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
47
Strength to Weight: Axial, points 21 to 24
40
Strength to Weight: Bending, points 20 to 22
42
Thermal Diffusivity, mm2/s 10
62
Thermal Shock Resistance, points 18 to 20
19

Alloy Composition

Aluminum (Al), % 0
92.4 to 94.9
Carbon (C), % 0.43 to 0.48
0
Chromium (Cr), % 0.4 to 0.6
0
Copper (Cu), % 0
1.9 to 2.7
Iron (Fe), % 96.5 to 97.7
0.9 to 1.3
Magnesium (Mg), % 0
1.3 to 1.8
Manganese (Mn), % 0.75 to 1.0
0
Molybdenum (Mo), % 0.15 to 0.25
0
Nickel (Ni), % 0.4 to 0.7
0.9 to 1.2
Phosphorus (P), % 0 to 0.035
0
Silicon (Si), % 0.15 to 0.35
0.1 to 0.25
Sulfur (S), % 0 to 0.040
0
Titanium (Ti), % 0
0.040 to 0.1
Zinc (Zn), % 0
0 to 0.1
Residuals, % 0
0 to 0.15