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R31538 Cobalt vs. S32750 Stainless Steel

R31538 cobalt belongs to the cobalt alloys classification, while S32750 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 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 R31538 cobalt and the bottom bar is S32750 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
210
Elongation at Break, % 13 to 23
17
Fatigue Strength, MPa 310 to 480
360
Poisson's Ratio 0.29
0.27
Rockwell C Hardness 25 to 35
28
Shear Modulus, GPa 86
81
Tensile Strength: Ultimate (UTS), MPa 1020 to 1360
860
Tensile Strength: Yield (Proof), MPa 580 to 930
590

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
15
Thermal Expansion, µm/m-K 13
12

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
4.1
Embodied Energy, MJ/kg 110
56
Embodied Water, L/kg 530
180

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
130
Resilience: Unit (Modulus of Resilience), kJ/m3 750 to 1920
860
Stiffness to Weight: Axial, points 15
15
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 34 to 45
31
Strength to Weight: Bending, points 27 to 32
26
Thermal Diffusivity, mm2/s 3.5
4.0
Thermal Shock Resistance, points 25 to 33
25

Alloy Composition

Carbon (C), % 0.15 to 0.35
0 to 0.030
Chromium (Cr), % 26 to 30
24 to 26
Cobalt (Co), % 58.7 to 68.9
0
Copper (Cu), % 0
0 to 0.5
Iron (Fe), % 0 to 0.75
58.1 to 66.8
Manganese (Mn), % 0 to 1.0
0 to 1.2
Molybdenum (Mo), % 5.0 to 7.0
3.0 to 5.0
Nickel (Ni), % 0 to 1.0
6.0 to 8.0
Nitrogen (N), % 0 to 0.25
0.24 to 0.32
Phosphorus (P), % 0
0 to 0.035
Silicon (Si), % 0 to 1.0
0 to 0.8
Sulfur (S), % 0
0 to 0.020