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R30021 Cobalt vs. S44800 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S44800 stainless steel belongs to the iron alloys. They have a modest 35% 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 S44800 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
210
Elongation at Break, % 9.0
23
Fatigue Strength, MPa 250
300
Poisson's Ratio 0.29
0.27
Rockwell C Hardness 32
18
Shear Modulus, GPa 86
82
Tensile Strength: Ultimate (UTS), MPa 700
590
Tensile Strength: Yield (Proof), MPa 500
450

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
480
Thermal Conductivity, W/m-K 15
17
Thermal Expansion, µm/m-K 11
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.6
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
3.0

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.8
Embodied Carbon, kg CO2/kg material 8.0
3.8
Embodied Energy, MJ/kg 110
52
Embodied Water, L/kg 520
190

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
120
Resilience: Unit (Modulus of Resilience), kJ/m3 570
480
Stiffness to Weight: Axial, points 15
15
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
21
Strength to Weight: Bending, points 21
20
Thermal Diffusivity, mm2/s 3.8
4.6
Thermal Shock Resistance, points 21
19

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.010
Chromium (Cr), % 26 to 29
28 to 30
Cobalt (Co), % 61.7 to 67.3
0
Copper (Cu), % 0
0 to 0.15
Iron (Fe), % 0 to 3.0
62.6 to 66.5
Manganese (Mn), % 0
0 to 0.3
Molybdenum (Mo), % 4.5 to 6.0
3.5 to 4.2
Nickel (Ni), % 2.0 to 3.0
2.0 to 2.5
Nitrogen (N), % 0
0 to 0.020
Phosphorus (P), % 0
0 to 0.025
Silicon (Si), % 0 to 1.5
0 to 0.2
Sulfur (S), % 0
0 to 0.020