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R30021 Cobalt vs. S39274 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S39274 stainless steel belongs to the iron alloys. They have a modest 32% 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 S39274 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
210
Elongation at Break, % 9.0
17
Fatigue Strength, MPa 250
380
Poisson's Ratio 0.29
0.27
Rockwell C Hardness 32
28
Shear Modulus, GPa 86
81
Tensile Strength: Ultimate (UTS), MPa 700
900
Tensile Strength: Yield (Proof), MPa 500
620

Thermal Properties

Latent Heat of Fusion, J/g 330
300
Melting Completion (Liquidus), °C 1350
1480
Melting Onset (Solidus), °C 1190
1430
Specific Heat Capacity, J/kg-K 450
470
Thermal Conductivity, W/m-K 15
16
Thermal Expansion, µm/m-K 11
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.4

Otherwise Unclassified Properties

Density, g/cm3 8.4
8.0
Embodied Carbon, kg CO2/kg material 8.0
4.3
Embodied Energy, MJ/kg 110
60
Embodied Water, L/kg 520
180

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
140
Resilience: Unit (Modulus of Resilience), kJ/m3 570
940
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
32
Strength to Weight: Bending, points 21
26
Thermal Diffusivity, mm2/s 3.8
4.2
Thermal Shock Resistance, points 21
25

Alloy Composition

Carbon (C), % 0.2 to 0.35
0 to 0.030
Chromium (Cr), % 26 to 29
24 to 26
Cobalt (Co), % 61.7 to 67.3
0
Copper (Cu), % 0
0.2 to 0.8
Iron (Fe), % 0 to 3.0
57 to 65.6
Manganese (Mn), % 0
0 to 1.0
Molybdenum (Mo), % 4.5 to 6.0
2.5 to 3.5
Nickel (Ni), % 2.0 to 3.0
6.0 to 8.0
Nitrogen (N), % 0
0.24 to 0.32
Phosphorus (P), % 0
0 to 0.030
Silicon (Si), % 0 to 1.5
0 to 0.8
Sulfur (S), % 0
0 to 0.020
Tungsten (W), % 0
1.5 to 2.5