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R31538 Cobalt vs. S31254 Stainless Steel

R31538 cobalt belongs to the cobalt alloys classification, while S31254 stainless steel belongs to the iron alloys. They have a modest 28% 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 R31538 cobalt and the bottom bar is S31254 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 13 to 23
40
Fatigue Strength, MPa 310 to 480
290
Poisson's Ratio 0.29
0.28
Reduction in Area, % 13 to 22
56
Shear Modulus, GPa 86
80
Tensile Strength: Ultimate (UTS), MPa 1020 to 1360
720
Tensile Strength: Yield (Proof), MPa 580 to 930
330

Thermal Properties

Latent Heat of Fusion, J/g 320
300
Melting Completion (Liquidus), °C 1360
1460
Melting Onset (Solidus), °C 1290
1420
Specific Heat Capacity, J/kg-K 450
460
Thermal Conductivity, W/m-K 13
14
Thermal Expansion, µm/m-K 13
17

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.3

Otherwise Unclassified Properties

Density, g/cm3 8.4
8.0
Embodied Carbon, kg CO2/kg material 8.1
5.5
Embodied Energy, MJ/kg 110
74
Embodied Water, L/kg 530
190

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
240
Resilience: Unit (Modulus of Resilience), kJ/m3 750 to 1920
270
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 34 to 45
25
Strength to Weight: Bending, points 27 to 32
22
Thermal Diffusivity, mm2/s 3.5
3.8
Thermal Shock Resistance, points 25 to 33
15

Alloy Composition

Carbon (C), % 0.15 to 0.35
0 to 0.020
Chromium (Cr), % 26 to 30
19.5 to 20.5
Cobalt (Co), % 58.7 to 68.9
0
Copper (Cu), % 0
0.5 to 1.0
Iron (Fe), % 0 to 0.75
51.4 to 56.3
Manganese (Mn), % 0 to 1.0
0 to 1.0
Molybdenum (Mo), % 5.0 to 7.0
6.0 to 6.5
Nickel (Ni), % 0 to 1.0
17.5 to 18.5
Nitrogen (N), % 0 to 0.25
0.18 to 0.22
Phosphorus (P), % 0
0 to 0.030
Silicon (Si), % 0 to 1.0
0 to 0.8
Sulfur (S), % 0
0 to 0.010