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G-CoCr28 Cobalt vs. S21640 Stainless Steel

G-CoCr28 cobalt belongs to the cobalt alloys classification, while S21640 stainless steel belongs to the iron alloys. They have a modest 39% 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 (6, in this case) are not shown.

For each property being compared, the top bar is G-CoCr28 cobalt and the bottom bar is S21640 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 210
200
Elongation at Break, % 6.7
46
Fatigue Strength, MPa 130
320
Poisson's Ratio 0.28
0.28
Shear Modulus, GPa 83
78
Tensile Strength: Ultimate (UTS), MPa 560
740
Tensile Strength: Yield (Proof), MPa 260
350

Thermal Properties

Latent Heat of Fusion, J/g 320
290
Maximum Temperature: Mechanical, °C 1200
940
Melting Completion (Liquidus), °C 1330
1430
Melting Onset (Solidus), °C 1270
1380
Specific Heat Capacity, J/kg-K 470
480
Thermal Conductivity, W/m-K 8.5
15
Thermal Expansion, µm/m-K 14
17

Otherwise Unclassified Properties

Base Metal Price, % relative 100
17
Density, g/cm3 8.1
7.7
Embodied Carbon, kg CO2/kg material 6.2
3.6
Embodied Energy, MJ/kg 84
51
Embodied Water, L/kg 440
150

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 31
280
Resilience: Unit (Modulus of Resilience), kJ/m3 160
300
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 19
27
Strength to Weight: Bending, points 19
23
Thermal Diffusivity, mm2/s 2.2
4.0
Thermal Shock Resistance, points 14
16

Alloy Composition

Carbon (C), % 0.050 to 0.25
0 to 0.080
Chromium (Cr), % 27 to 30
17.5 to 19.5
Cobalt (Co), % 48 to 52
0
Iron (Fe), % 9.7 to 24.5
63 to 74.3
Manganese (Mn), % 0 to 1.5
3.5 to 6.5
Molybdenum (Mo), % 0 to 0.5
0.5 to 2.0
Nickel (Ni), % 0 to 4.0
4.0 to 6.5
Niobium (Nb), % 0 to 0.5
0.1 to 1.0
Nitrogen (N), % 0
0.080 to 0.3
Phosphorus (P), % 0 to 0.040
0 to 0.060
Silicon (Si), % 0.5 to 1.5
0 to 1.0
Sulfur (S), % 0 to 0.030
0 to 0.030