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R30021 Cobalt vs. S17700 Stainless Steel

R30021 cobalt belongs to the cobalt alloys classification, while S17700 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 28 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 S17700 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 9.0
1.0 to 23
Fatigue Strength, MPa 250
290 to 560
Poisson's Ratio 0.29
0.28
Rockwell C Hardness 32
41 to 46
Shear Modulus, GPa 86
76
Tensile Strength: Ultimate (UTS), MPa 700
1180 to 1650
Tensile Strength: Yield (Proof), MPa 500
430 to 1210

Thermal Properties

Latent Heat of Fusion, J/g 330
290
Melting Completion (Liquidus), °C 1350
1440
Melting Onset (Solidus), °C 1190
1400
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 15
15
Thermal Expansion, µm/m-K 11
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 1.9
2.3
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.7

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.7
Embodied Carbon, kg CO2/kg material 8.0
2.8
Embodied Energy, MJ/kg 110
40
Embodied Water, L/kg 520
150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 57
15 to 210
Resilience: Unit (Modulus of Resilience), kJ/m3 570
460 to 3750
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 23
42 to 59
Strength to Weight: Bending, points 21
32 to 40
Thermal Diffusivity, mm2/s 3.8
4.1
Thermal Shock Resistance, points 21
39 to 54

Alloy Composition

Aluminum (Al), % 0
0.75 to 1.5
Carbon (C), % 0.2 to 0.35
0 to 0.090
Chromium (Cr), % 26 to 29
16 to 18
Cobalt (Co), % 61.7 to 67.3
0
Iron (Fe), % 0 to 3.0
70.5 to 76.8
Manganese (Mn), % 0
0 to 1.0
Molybdenum (Mo), % 4.5 to 6.0
0
Nickel (Ni), % 2.0 to 3.0
6.5 to 7.8
Phosphorus (P), % 0
0 to 0.040
Silicon (Si), % 0 to 1.5
0 to 1.0
Sulfur (S), % 0
0 to 0.030