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SAE-AISI A8 Steel vs. R31538 Cobalt

SAE-AISI A8 steel belongs to the iron alloys classification, while R31538 cobalt belongs to the cobalt alloys. There are 22 material properties with values for both materials. Properties with values for just one material (9, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI A8 steel and the bottom bar is R31538 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
220
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 74
86
Tensile Strength: Ultimate (UTS), MPa 700 to 1920
1020 to 1360

Thermal Properties

Latent Heat of Fusion, J/g 270
320
Melting Completion (Liquidus), °C 1480
1360
Melting Onset (Solidus), °C 1430
1290
Specific Heat Capacity, J/kg-K 470
450
Thermal Conductivity, W/m-K 37
13
Thermal Expansion, µm/m-K 12
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 8.3
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 9.5
2.1

Otherwise Unclassified Properties

Density, g/cm3 7.9
8.4
Embodied Carbon, kg CO2/kg material 2.3
8.1
Embodied Energy, MJ/kg 31
110
Embodied Water, L/kg 73
530

Common Calculations

Stiffness to Weight: Axial, points 14
15
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 25 to 68
34 to 45
Strength to Weight: Bending, points 22 to 44
27 to 32
Thermal Diffusivity, mm2/s 9.9
3.5
Thermal Shock Resistance, points 22 to 62
25 to 33

Alloy Composition

Carbon (C), % 0.5 to 0.6
0.15 to 0.35
Chromium (Cr), % 4.8 to 5.5
26 to 30
Cobalt (Co), % 0
58.7 to 68.9
Copper (Cu), % 0 to 0.25
0
Iron (Fe), % 88.5 to 91.9
0 to 0.75
Manganese (Mn), % 0 to 0.5
0 to 1.0
Molybdenum (Mo), % 1.2 to 1.7
5.0 to 7.0
Nickel (Ni), % 0 to 0.3
0 to 1.0
Nitrogen (N), % 0
0 to 0.25
Phosphorus (P), % 0 to 0.030
0
Silicon (Si), % 0.75 to 1.1
0 to 1.0
Sulfur (S), % 0 to 0.030
0
Tungsten (W), % 1.0 to 1.5
0

Comparable Variants