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R30816 Cobalt vs. S82121 Stainless Steel

R30816 cobalt belongs to the cobalt alloys classification, while S82121 stainless steel belongs to the iron alloys. They have a modest 28% of their average alloy composition in common, which, by itself, doesn't mean much. There are 26 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 R30816 cobalt and the bottom bar is S82121 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 280
250
Elastic (Young's, Tensile) Modulus, GPa 210
200
Elongation at Break, % 23
28
Fatigue Strength, MPa 250
370
Poisson's Ratio 0.3
0.27
Shear Modulus, GPa 81
78
Tensile Strength: Ultimate (UTS), MPa 1020
730
Tensile Strength: Yield (Proof), MPa 460
510

Thermal Properties

Latent Heat of Fusion, J/g 300
290
Melting Completion (Liquidus), °C 1540
1430
Melting Onset (Solidus), °C 1460
1380
Specific Heat Capacity, J/kg-K 420
480
Thermal Conductivity, W/m-K 13
15
Thermal Expansion, µm/m-K 12
13

Otherwise Unclassified Properties

Density, g/cm3 9.1
7.7
Embodied Carbon, kg CO2/kg material 20
2.8
Embodied Energy, MJ/kg 320
40
Embodied Water, L/kg 440
150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 190
180
Resilience: Unit (Modulus of Resilience), kJ/m3 510
660
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 22
25
Strength to Weight: Axial, points 31
26
Strength to Weight: Bending, points 25
23
Thermal Diffusivity, mm2/s 3.3
4.0
Thermal Shock Resistance, points 28
20

Alloy Composition

Carbon (C), % 0.32 to 0.42
0 to 0.035
Chromium (Cr), % 19 to 21
21 to 23
Cobalt (Co), % 40 to 49.8
0
Copper (Cu), % 0
0.2 to 1.2
Iron (Fe), % 0 to 5.0
66.7 to 75.4
Manganese (Mn), % 1.0 to 2.0
1.0 to 2.5
Molybdenum (Mo), % 3.5 to 4.5
0.3 to 1.3
Nickel (Ni), % 19 to 21
2.0 to 4.0
Niobium (Nb), % 3.5 to 4.5
0
Nitrogen (N), % 0
0.15 to 0.25
Phosphorus (P), % 0 to 0.040
0 to 0.040
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0 to 0.030
0 to 0.010
Tantalum (Ta), % 3.5 to 4.5
0
Tungsten (W), % 3.5 to 4.5
0