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R30021 Cobalt vs. ACI-ASTM CK20 Steel

R30021 cobalt belongs to the cobalt alloys classification, while ACI-ASTM CK20 steel belongs to the iron alloys. They have a modest 30% 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 (7, in this case) are not shown.

For each property being compared, the top bar is R30021 cobalt and the bottom bar is ACI-ASTM CK20 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 9.0
37
Fatigue Strength, MPa 250
220
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 86
78
Tensile Strength: Ultimate (UTS), MPa 700
530
Tensile Strength: Yield (Proof), MPa 500
260

Thermal Properties

Latent Heat of Fusion, J/g 330
310
Melting Completion (Liquidus), °C 1350
1400
Melting Onset (Solidus), °C 1190
1430
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 15
14
Thermal Expansion, µm/m-K 11
15

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.3

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.8
Embodied Carbon, kg CO2/kg material 8.0
4.4
Embodied Energy, MJ/kg 110
62
Embodied Water, L/kg 520
190

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
160
Resilience: Unit (Modulus of Resilience), kJ/m3 570
170
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
19
Strength to Weight: Bending, points 21
19
Thermal Diffusivity, mm2/s 3.8
3.7
Thermal Shock Resistance, points 21
13

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.2
Chromium (Cr), % 26 to 29
23 to 27
Cobalt (Co), % 61.7 to 67.3
0
Iron (Fe), % 0 to 3.0
46.7 to 58
Manganese (Mn), % 0
0 to 2.0
Molybdenum (Mo), % 4.5 to 6.0
0 to 0.5
Nickel (Ni), % 2.0 to 3.0
19 to 22
Phosphorus (P), % 0
0 to 0.040
Silicon (Si), % 0 to 1.5
0 to 2.0
Sulfur (S), % 0
0 to 0.040