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R30021 Cobalt vs. S39277 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S39277 stainless steel belongs to the iron alloys. They have a modest 33% of their average alloy composition in common, which, by itself, doesn't mean much. 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 R30021 cobalt and the bottom bar is S39277 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 9.0
28
Fatigue Strength, MPa 250
480
Poisson's Ratio 0.29
0.27
Shear Modulus, GPa 86
80
Tensile Strength: Ultimate (UTS), MPa 700
930
Tensile Strength: Yield (Proof), MPa 500
660

Thermal Properties

Latent Heat of Fusion, J/g 330
300
Melting Completion (Liquidus), °C 1350
1460
Melting Onset (Solidus), °C 1190
1410
Specific Heat Capacity, J/kg-K 450
470
Thermal Conductivity, W/m-K 15
16
Thermal Expansion, µm/m-K 11
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.5

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.9
Embodied Carbon, kg CO2/kg material 8.0
4.2
Embodied Energy, MJ/kg 110
59
Embodied Water, L/kg 520
180

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
240
Resilience: Unit (Modulus of Resilience), kJ/m3 570
1070
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
33
Strength to Weight: Bending, points 21
27
Thermal Diffusivity, mm2/s 3.8
4.2
Thermal Shock Resistance, points 21
26

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.025
Chromium (Cr), % 26 to 29
24 to 26
Cobalt (Co), % 61.7 to 67.3
0
Copper (Cu), % 0
1.2 to 2.0
Iron (Fe), % 0 to 3.0
56.8 to 64.3
Manganese (Mn), % 0
0 to 0.8
Molybdenum (Mo), % 4.5 to 6.0
3.0 to 4.0
Nickel (Ni), % 2.0 to 3.0
6.5 to 8.0
Nitrogen (N), % 0
0.23 to 0.33
Phosphorus (P), % 0
0 to 0.025
Silicon (Si), % 0 to 1.5
0 to 0.8
Sulfur (S), % 0
0 to 0.0020
Tungsten (W), % 0
0.8 to 1.2