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R30021 Cobalt vs. S45000 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S45000 stainless steel belongs to the iron alloys. They have a modest 20% 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 (8, in this case) are not shown.

For each property being compared, the top bar is R30021 cobalt and the bottom bar is S45000 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 9.0
6.8 to 14
Fatigue Strength, MPa 250
330 to 650
Poisson's Ratio 0.29
0.28
Rockwell C Hardness 32
28 to 44
Shear Modulus, GPa 86
76
Tensile Strength: Ultimate (UTS), MPa 700
980 to 1410
Tensile Strength: Yield (Proof), MPa 500
580 to 1310

Thermal Properties

Latent Heat of Fusion, J/g 330
280
Melting Completion (Liquidus), °C 1350
1440
Melting Onset (Solidus), °C 1190
1390
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 15
17
Thermal Expansion, µm/m-K 11
11

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
7.8
Embodied Carbon, kg CO2/kg material 8.0
2.8
Embodied Energy, MJ/kg 110
39
Embodied Water, L/kg 520
130

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
94 to 160
Resilience: Unit (Modulus of Resilience), kJ/m3 570
850 to 4400
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
35 to 50
Strength to Weight: Bending, points 21
28 to 36
Thermal Diffusivity, mm2/s 3.8
4.5
Thermal Shock Resistance, points 21
33 to 47

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.050
Chromium (Cr), % 26 to 29
14 to 16
Cobalt (Co), % 61.7 to 67.3
0
Copper (Cu), % 0
1.3 to 1.8
Iron (Fe), % 0 to 3.0
72.1 to 79.3
Manganese (Mn), % 0
0 to 1.0
Molybdenum (Mo), % 4.5 to 6.0
0.5 to 1.0
Nickel (Ni), % 2.0 to 3.0
5.0 to 7.0
Phosphorus (P), % 0
0 to 0.040
Silicon (Si), % 0 to 1.5
0 to 1.0
Sulfur (S), % 0
0 to 0.030