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R30021 Cobalt vs. S31100 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S31100 stainless steel belongs to the iron alloys. They have a modest 31% of their average alloy composition in common, which, by itself, doesn't mean much. There are 28 material properties with values for both materials. Properties with values for just one material (7, in this case) are not shown.

For each property being compared, the top bar is R30021 cobalt and the bottom bar is S31100 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 9.0
4.5
Fatigue Strength, MPa 250
330
Poisson's Ratio 0.29
0.27
Rockwell C Hardness 32
28
Shear Modulus, GPa 86
79
Tensile Strength: Ultimate (UTS), MPa 700
1000
Tensile Strength: Yield (Proof), MPa 500
710

Thermal Properties

Latent Heat of Fusion, J/g 330
300
Melting Completion (Liquidus), °C 1350
1420
Melting Onset (Solidus), °C 1190
1380
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 15
16
Thermal Expansion, µm/m-K 11
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.4

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.7
Embodied Carbon, kg CO2/kg material 8.0
3.1
Embodied Energy, MJ/kg 110
44
Embodied Water, L/kg 520
170

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
40
Resilience: Unit (Modulus of Resilience), kJ/m3 570
1240
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
36
Strength to Weight: Bending, points 21
29
Thermal Diffusivity, mm2/s 3.8
4.2
Thermal Shock Resistance, points 21
28

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.060
Chromium (Cr), % 26 to 29
25 to 27
Cobalt (Co), % 61.7 to 67.3
0
Iron (Fe), % 0 to 3.0
63.6 to 69
Manganese (Mn), % 0
0 to 1.0
Molybdenum (Mo), % 4.5 to 6.0
0
Nickel (Ni), % 2.0 to 3.0
6.0 to 7.0
Phosphorus (P), % 0
0 to 0.045
Silicon (Si), % 0 to 1.5
0 to 1.0
Sulfur (S), % 0
0 to 0.030
Titanium (Ti), % 0
0 to 0.25