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SAE-AISI 8740 Steel vs. R30016 Cobalt

SAE-AISI 8740 steel belongs to the iron alloys classification, while R30016 cobalt belongs to the cobalt alloys. There are 27 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 8740 steel and the bottom bar is R30016 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
220
Elongation at Break, % 11 to 23
8.4
Fatigue Strength, MPa 270 to 350
290
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 73
85
Tensile Strength: Ultimate (UTS), MPa 580 to 670
1010
Tensile Strength: Yield (Proof), MPa 380 to 570
580

Thermal Properties

Latent Heat of Fusion, J/g 250
320
Melting Completion (Liquidus), °C 1460
1360
Melting Onset (Solidus), °C 1420
1270
Specific Heat Capacity, J/kg-K 470
450
Thermal Conductivity, W/m-K 39
15
Thermal Expansion, µm/m-K 13
14

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.3
1.9
Electrical Conductivity: Equal Weight (Specific), % IACS 8.4
2.0

Otherwise Unclassified Properties

Density, g/cm3 7.8
8.5
Embodied Carbon, kg CO2/kg material 1.5
7.7
Embodied Energy, MJ/kg 20
110
Embodied Water, L/kg 50
500

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 71 to 120
72
Resilience: Unit (Modulus of Resilience), kJ/m3 390 to 850
770
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 20 to 24
33
Strength to Weight: Bending, points 20 to 22
26
Thermal Diffusivity, mm2/s 10
3.9
Thermal Shock Resistance, points 17 to 20
24

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.9 to 1.4
Chromium (Cr), % 0.4 to 0.6
28 to 32
Cobalt (Co), % 0
49.6 to 66.9
Iron (Fe), % 96.5 to 97.7
0 to 3.0
Manganese (Mn), % 0.75 to 1.0
0.5 to 2.0
Molybdenum (Mo), % 0.2 to 0.3
0 to 1.5
Nickel (Ni), % 0.4 to 0.7
0 to 3.0
Phosphorus (P), % 0 to 0.035
0
Silicon (Si), % 0.15 to 0.35
0.2 to 2.0
Sulfur (S), % 0 to 0.040
0
Tungsten (W), % 0
3.5 to 5.5