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R31537 Cobalt vs. S31803 Stainless Steel

R31537 cobalt belongs to the cobalt alloys classification, while S31803 stainless steel belongs to the iron alloys. They have a modest 27% of their average alloy composition in common, which, by itself, doesn't mean much. There are 29 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 R31537 cobalt and the bottom bar is S31803 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 14 to 23
29
Fatigue Strength, MPa 310 to 480
370
Poisson's Ratio 0.29
0.27
Reduction in Area, % 13 to 23
50
Rockwell C Hardness 25 to 35
27
Shear Modulus, GPa 87
80
Tensile Strength: Ultimate (UTS), MPa 1000 to 1340
710
Tensile Strength: Yield (Proof), MPa 590 to 940
500

Thermal Properties

Latent Heat of Fusion, J/g 320
300
Melting Completion (Liquidus), °C 1360
1450
Melting Onset (Solidus), °C 1290
1400
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 13
16
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.5

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.8
Embodied Carbon, kg CO2/kg material 8.1
3.6
Embodied Energy, MJ/kg 110
49
Embodied Water, L/kg 530
160

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
180
Resilience: Unit (Modulus of Resilience), kJ/m3 780 to 1990
630
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 33 to 44
25
Strength to Weight: Bending, points 26 to 32
23
Thermal Diffusivity, mm2/s 3.4
4.3
Thermal Shock Resistance, points 24 to 32
20

Alloy Composition

Carbon (C), % 0 to 0.14
0 to 0.030
Chromium (Cr), % 26 to 30
21 to 23
Cobalt (Co), % 58.9 to 69
0
Iron (Fe), % 0 to 0.75
63.7 to 71.9
Manganese (Mn), % 0 to 1.0
0 to 2.0
Molybdenum (Mo), % 5.0 to 7.0
2.5 to 3.5
Nickel (Ni), % 0 to 1.0
4.5 to 6.5
Nitrogen (N), % 0 to 0.25
0.080 to 0.2
Phosphorus (P), % 0
0 to 0.030
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0
0 to 0.020