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R30816 Cobalt vs. S21904 Stainless Steel

R30816 cobalt belongs to the cobalt alloys classification, while S21904 stainless steel belongs to the iron alloys. They have a modest 31% of their average alloy composition in common, which, by itself, doesn't mean much. There are 26 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 R30816 cobalt and the bottom bar is S21904 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 280
210 to 300
Elastic (Young's, Tensile) Modulus, GPa 210
200
Elongation at Break, % 23
17 to 51
Fatigue Strength, MPa 250
380 to 550
Poisson's Ratio 0.3
0.28
Shear Modulus, GPa 81
78
Tensile Strength: Ultimate (UTS), MPa 1020
700 to 1000
Tensile Strength: Yield (Proof), MPa 460
390 to 910

Thermal Properties

Latent Heat of Fusion, J/g 300
290
Melting Completion (Liquidus), °C 1540
1400
Melting Onset (Solidus), °C 1460
1350
Specific Heat Capacity, J/kg-K 420
480
Thermal Conductivity, W/m-K 13
14
Thermal Expansion, µm/m-K 12
17

Otherwise Unclassified Properties

Density, g/cm3 9.1
7.7
Embodied Carbon, kg CO2/kg material 20
3.0
Embodied Energy, MJ/kg 320
43
Embodied Water, L/kg 440
160

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 190
160 to 310
Resilience: Unit (Modulus of Resilience), kJ/m3 510
380 to 2070
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 22
25
Strength to Weight: Axial, points 31
25 to 36
Strength to Weight: Bending, points 25
23 to 29
Thermal Diffusivity, mm2/s 3.3
3.8
Thermal Shock Resistance, points 28
15 to 21

Alloy Composition

Carbon (C), % 0.32 to 0.42
0 to 0.040
Chromium (Cr), % 19 to 21
19 to 21.5
Cobalt (Co), % 40 to 49.8
0
Iron (Fe), % 0 to 5.0
59.5 to 67.4
Manganese (Mn), % 1.0 to 2.0
8.0 to 10
Molybdenum (Mo), % 3.5 to 4.5
0
Nickel (Ni), % 19 to 21
5.5 to 7.5
Niobium (Nb), % 3.5 to 4.5
0
Nitrogen (N), % 0
0.15 to 0.4
Phosphorus (P), % 0 to 0.040
0 to 0.045
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0 to 0.030
0 to 0.030
Tantalum (Ta), % 3.5 to 4.5
0
Tungsten (W), % 3.5 to 4.5
0