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R30075 Cobalt vs. S21640 Stainless Steel

R30075 cobalt belongs to the cobalt alloys classification, while S21640 stainless steel belongs to the iron alloys. They have a modest 22% 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 R30075 cobalt and the bottom bar is S21640 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 210 to 250
200
Elongation at Break, % 12
46
Fatigue Strength, MPa 250 to 840
320
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 82 to 98
78
Tensile Strength: Ultimate (UTS), MPa 780 to 1280
740
Tensile Strength: Yield (Proof), MPa 480 to 840
350

Thermal Properties

Latent Heat of Fusion, J/g 320
290
Melting Completion (Liquidus), °C 1360
1430
Melting Onset (Solidus), °C 1290
1380
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 13
15
Thermal Expansion, µm/m-K 12
17

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
2.4
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.8

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.7
Embodied Carbon, kg CO2/kg material 8.1
3.6
Embodied Energy, MJ/kg 110
51
Embodied Water, L/kg 530
150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 84 to 140
280
Resilience: Unit (Modulus of Resilience), kJ/m3 560 to 1410
300
Stiffness to Weight: Axial, points 14 to 17
14
Stiffness to Weight: Bending, points 24 to 25
25
Strength to Weight: Axial, points 26 to 42
27
Strength to Weight: Bending, points 22 to 31
23
Thermal Diffusivity, mm2/s 3.5
4.0
Thermal Shock Resistance, points 21 to 29
16

Alloy Composition

Aluminum (Al), % 0 to 0.1
0
Boron (B), % 0 to 0.010
0
Carbon (C), % 0 to 0.35
0 to 0.080
Chromium (Cr), % 27 to 30
17.5 to 19.5
Cobalt (Co), % 58.7 to 68
0
Iron (Fe), % 0 to 0.75
63 to 74.3
Manganese (Mn), % 0 to 1.0
3.5 to 6.5
Molybdenum (Mo), % 5.0 to 7.0
0.5 to 2.0
Nickel (Ni), % 0 to 0.5
4.0 to 6.5
Niobium (Nb), % 0
0.1 to 1.0
Nitrogen (N), % 0 to 0.25
0.080 to 0.3
Phosphorus (P), % 0 to 0.020
0 to 0.060
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0 to 0.010
0 to 0.030
Titanium (Ti), % 0 to 0.1
0
Tungsten (W), % 0 to 0.2
0